I did a search and didn't find anything this on these boards, so I thought I'd give it a go. This is largely based on this varient, but with a few alterations.
Much of this is down to the DM and requires a lot of DM judgement calls, so it's not for everyone. This table is helpful for deciding what should and should not provide reputation, but no task will gain more than half a reputation point at a time.
There is no morality associated with reputation, except that reputations are gained "for" things. Consistancy is key and a character will continue to earn reputation so long as they stay true to form. A Paladin that saves villages from dragons will continue to earn reputation so long as they continue to do things seen as just and good. If that Paladin has a change of heart and starts to eat babies, they will start to lose reputation. Once your reputation reaches half its maximum value, what you are famous for changes to what ever you have been doing to lose reputation. Whenever a character completes a task with a high enough public profile they gain 1/2 a reputation point at a time. If, for what ever reason, begin to lose reputation, they lose 1 reputation point at a time. Reputations are easier to lose than they are to build. Your reputation can never be higher than your level+3.
For example a level 5 Fighter has been working as a mercenary for a while now and has a reputation as a hired sword who will work for the highest bidder and has a reputation score of 8. He and his band are hired to slay a village for not paying their taxes by an evil lord, but at the last minute he has a change of heart and instead decides to protect them. His reputation drops to 7. He continues in this vein, protecting the village from raids by the local lord, losing 1 reputation for each time he helps them. Once his reputation hits 4, he instead starts to become known as a champion of the downtrodden. He will start to gain reputation for "good" acts, rather than for completing successful mercenary missions.
Mechanical Benefits of Reputation
For every 5 points of reputation a character gain a +1 untyped bonus to his leadership score, intimidate checks and diplomacy checks. Disguise checks take a -1 untyped penalty per 5 points of reputation. Other characters take a -2 untyped penalty per 5 points of your reputation to disguise themselves as you or forge your signature with the forgery skill.
Divine (entirely optional to the campaign) People's belief in you is so great that you are raised to godhood. Prerequisites: Reputation 21, Worthy of Song, Legendary, Mythical (and one of Weapon Focus, Great Fortitude, Lightning Reflexes, Iron WIll or Skill Focus), death Benefit: You are ressurected as if with a true ressurection spell and gain divine rank 0. Special: If you meet all the prerequisites, you instantly gain this feat. It cannot be taken by a living, or undead, character. Normal: Dead people rot.
Legendary Your deeds are so great that they are spoken about far and wide Prerequisites: Reputation 12, Worthy of Song (and one of Weapon Focus, Great Fortitude, Lightning Reflexes, Iron Will or Skill Focus) Benefit: When using your bonus from Worthy of Song, 1/encounter you may add your full reputation bonus. Special: You may take this feat multiple times. Each time you take it, it applies to another usage of Worthy of Song that you have, or adds a new use /encounter to a check you can already use Worthy of Song with 2/encounter. You must apply this bonus to a skill, save or weapon that you can use Worthy of Song with. A fighter may take this as one of his fighter bonus feats.
Normal: Worthy of Song only allows you to add half your reputation bonus to skills.
Mythical Your actions are known far and wide and are told as tales to children. They are great enough that some people think of them as mere tales of fantasy. Prerequisites: Reputation 18, Worthy of Song, Legendary (and one of Weapon Focus, Great Fortitude, Lightning Reflexes, Iron Will or Skill Focus) Benefit: When using your bonus from Worthy of Song and Legendary with a weapon, you may add half your reputation bonus (rounded down) to the damage as well as your full reputation bonus to hit with your focused weapon. When using them with a skill or save, you may add 1.5x your reputation bonus (rounded down) to the check. Special: You may take this feat multiple times. Each time it applies to a new weapon, save or skill that you can use both Worthy of Song and Legendary with, or adds a new usage of Mythical to a check you can use both Worthy of Song and Legendary at least 2/encounter and Mythical at least 1/encounter with. A fighter may take this as one of his fighter bonus feats. You may not be able to use Mythical more times per day than Legendary or Worthy of Song Normal: Worthy of Song and Legendary do not increase the damage you can do with a weapon. They only allow you to add your full reputation bonus to saves and skill checks, and not 1.5x your reputation bonus.
Worthy of Song People sing of your deeds Prerequisites: Reputation 6 (and one of Weapon Focus, Great Fortitude, Lightning Reflexes, Iron Will or Skill Focus) Benefit: Pick either a weapon you already have weapon focus with, a save that a single feat has given you a +2 bonus to or a single skill you have skill focus in (eg: longsword, reflex saves or spellcraft). You can add half your reputation bonus, rounded down, to either attacks rolls made with that weapon, your save or your skill check 1/encounter. You must declare your useage of this bonus before you roll. Special: You can take this feat multiple times. Each time you take it, it either adds an extra usage per encounter to your current bonus, or applies to a new skill or weapon. A fighter may take this as one of his fighter bonus feats. Normal: Your reputation only provides minor bonuses
Reputation based class features
Known: At level 1 a Paladin gains 1 reputation point. They may not increase this one-time bonus through any means, not even their their Aura of Awe ability.
Aura of Awe: Paladins seem larger than life and their deeds seem greater because of it. From level 1 they may add an extra +1/2 to any reputation they earn. However, they fall from grace much more easily and will lose an extra 1 point of reputation whenever they lose reputation.
Smite Evil: As RAW, but instead of adding their Paladin level to damage, they add their Reputation Score.
Lay on Hands: As RAW, but instead of multiplying their charisma bonus by their Paladin Level to the amount they can heal, they multiply their charisma bonus by their reputation score.
Sing their Praises: From level 1, after an event (see this table for examples of what counts) a bard may make a perform check to increase his own and his party member's reputation scores by 1/2, though he may "leave out" any party members who don't want their praises sung. This may include events that would otherwise grant no reputation. There must be at least 10 people in the crowd per point of reputation of the highest reputation score in the party. The perform check DC is 15+the highest reputation score in the party. The higher a reputation, the harder it is to exaggurate it. This may only be done once for any given event.
Defame/Praise: From level 1, after meeting a person, a bard may make a perform check to decrease that person's reputation by 1 point, or increase it by 1/2 a point through the use of witty lyrics, or a particularly poigniant interpretive dance. This may only be done once for each time the bard has met that person, and any meetings must be more than 2 weeks apart. It is hard to come up with new material if they haven't done anything new. There must be 10 people in the crowd per point of reputation that person currently has.
RP effects of reputation
This is largely up to the DM to adjudicate, but in general reputation will affect how people react to you. Here are some guidelines for how to play it:
Rep 0: An unknown quantity. No one has heard of you and so your name carries no clout. Level 1 characters start at this. Example: You.
Rep 1-5: Known. Your actions have been heard of by some people. Depending on your reputation, people may act favourably towards you in minor ways like telling you that they think you're an ok bloke. Example: Any local hero.
Rep 6-10: Well known. Your actions have made you famous, to a certain extent. People sing songs about you, or make jokes about you. Depending on your reputation, people may give you discounts on certain things so that they can say you used their wares. Example: Any famous person, such as Bruce Willis.
Rep 11-15: Legendary. Your actions are so well known that some people think that you may just be a story. People will be supprised to meet you in person, unless they know you well. Example: Robin Hood.
Rep 16+: Mythical. Tales about you are so overblown that people don't really think you exist. If they meet you in person and find out who you are, they will either faint from excitement, or tell you to pull the other one as it is likely to be attached to bells. Example: Hercules.
Edit: Feats to Capitalise on a Low Reputation
Ignored In combat, you just don't seem to be an important target Prerequisites: Reputation score less than half your level, Underestimated Benefit: You do not need to be opposite an ally to gain a flanking bonus. 1/encounter you may negate an attack of oppertunity that you provoke. Special: A fighter can select this as one of his fighter bonus feats. Normal: You must be directly opposite an ally to gain a flanking bonus.
Incognito No one knows who you are, to the extent that it is hard to name you or even describe you as the subject of a spell Prerequisites: Disguise 13 ranks, Reputation 1/2 or less, Unknown Benefit: Truenamers cannot affect you with spells. Subtract your reputation from your level and divide by 2. 1/encounter you may add that as a bonus (rounded down) to fortitude and will saves. You must declare this before you roll. Special: If you gain anything more than 1/2 a reputation point, you lose the benefits of this feat. Normal: Having no reputation provides no bonuses.
Underestimated The way you hold yourself makes you seem less threatening Prerequsites: Reputation score lower than level Benefit: You provide no flanking bonus to your allies. Instead, subtract your reputation from your level and divide by 2. You gain the result (rounded down) as a bonus to attack rolls made while flanking. This is instead of the normal +2 gained from flanking. Special: A fighter can select this as one of his fighter bonus feats. Normal: You provide a +2 bonus to your allies attack rolls whilst flanking.
Unknown You just don't seem to stand out in crowds. Prerequisites: Reputation score lower than level. Benefit: Subtract your reputation score from your level and divide by 2. You gain the result (rounded down) as a bonus to disguise checks, hide checks, move silently checks and bluff checks. Edit: Other people take that result as a penalty to gather information checks to find anything out about you. Normal: A low reputation provides no bonuses.
Edit 2: Can I request that someone suggest ways for this to be useful to casters?
Edit 3: Alter Egos
Any character can create an alter-ego. Essentially, they disguise themselves as somebody else in the normal way. Their alter-ego has a reputation score of 0 when it is first created. The character counts as having two reputation scores for the sake of meeting prerequisites. If anybody ever sees through the disguise, you lose your lowest reputation score and any benefits you had associated with it. There will also probably be RP effects of this as well.
Bruze Haywayn (Original character, do not steal) is a billionaire who has broken WBL and is known fairly well within his community. He has a reputation of about 4. He is also, for some reason, an Unarmed Swordsage with the sacred vow and vow of nonviolence, but that and his convoluted backstory are not relevant to this discussion.
He wants to go out and fight crime, but he doesn't want his billionaire playboy lifestyle to be ruined by revenge shots. In a flash of genius, he dresses up as a bat. He now has an alter-ego and has a reputation of 5/0.
Over time, he reaches high levels. His alter-ego has amassed a prety high reputation for beating up criminals using nothing but non-lethal damage. His reputation at level 18 looks like this: 5/21. Over the course of his career he took the Worthy of Song, legendary and mythical feats to give him a bonus to attack rolls just incase he really needs to pull something out of the bag at the last minute.
1/encounter he may add +21 to attack rolls and +10 to damage (21/2=10.5, rounded down=10) from the mythical feat. He also took the unknown feat as his true identity has a reutation score lower than his level, so he qualifies. He subtracts his lowest reputation score from his level and divides by 2 to get 6 (18-5=13. 13/2=6.5, rounded down=6). He has a +6 bonus to disguise, hide, move silently and bluff checks from the unknown feat.
Later a ridiculous enemy that the DM cooked up at the last minute called the Riddle-meister discovers his true identity. Bruze loses his bonuses from unknown and incognito. He punches out the Riddle-meister before he can escape and tell anyone, so the DM rules that the Riddle-meister will suffer from amnesia and lets Bruze keep his bonuses.
This is an interesting concept that I'm considering working into a campaign I haven't quite started yet.
Do you think this is something that can/should be done without the players really knowing about it to try and avoid Meta-gaming and add a bit of surprise when they suddenly find themselves on the receiving end of some sweet deals and possibly even a True-res if they manage to become worthy enough?
Meddle not in the affairs of Dragons, unless you brought someone bigger and tastier along with you.
Well, I produced it with the idea that the players would be aware of their reputation score, but if you want to keep it hidden and then tell them suddenly that once per encounter (or day if you'd prefer) they get a huge bonus to an attack roll/save etc, be my guest. The Divine feat was designed with players not being aware of it in mind, but then you can't really critique a rule you don't know, so I was forced to put it up.
Also, the Bard abilities sort of assume that the bard player knows that reputation brings mechanical rewards so he has a reason to use them. No one uses a class ability for purely roleplay reasons all the time.
Edit: Oh and for E6 campaigns, remove the level+3 limit on reputation. Just because their abilities can't be overblown, doesn't mean that the tales told about them shouldn't be.
I read this and thought: this is cool, I should use this. Then I thought awsomesauce. And then I thought reputation based caster.
Couldn't think of any way for a caster to use this. I thought about adding reputation to caster level, but most of the time that would be a waste (eg, limits on max caster level for a spell) and when it's not, it's over-powering (spells lasting for 40 hours? 80 with extend? Yes please). Possibly add it to save DC's, but then that's a 1/encounter insta-gib with no chance of saving.
Could be useful for spellcraft checks, I suppose, but the real value is in the bonus to saves or attack rolls.
This is a post performing blatant thread necromancy.
I updated the rules a little and wanted some criticism of them. I'm concerned that 1/encounter may be too powerful for most of these abilities and wanted to check with the playgrounders. I'd also like some ideas for how casters can utilise these abilities, because I can't really see a decent way for it to happen.