Might want to add something about the factotum for multiclassing, and the mineral warrior template for +1 LA.

Factotum:
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For multiclassing, a primary warblade has 2 obvious factotum dips. Generally, factotum dips are best for WB's who already have a high int, or for higher ECL characters who have ways of boosting their int through items. Since you may already want to be boosting int to boost your "Battle" line of class features, this can be very profitable and add flexibility to your WB.
1. Two level dip:
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What you gain:
Improved reflex saves.
A cantrip (not big).
3 Inspiration Points per encounter.
Cunning Insight - For 1 IP and no action, add int mod to any attack roll, save, or damage roll as a competence bonus.
Cunning Knowledge - For 1 IP, get a +2 to any skill check.
Trapfinding.
A ton of extra skill points to spend on ANY(!!!) skill. Nice for giving that big guy with a sword a little perceptive ability, a little UMD, ability or whatever you need to fill out/assist party roles.

What you lose:
1 point of BAB, a few hp (d8 vs. d12), 1 IL.
You'll probably miss 1 maneuver known, and 1 maneuver re-train.
A Warblade class ability depending on level of the dip. You need to decide on the viability depending on what your WB does.

Good level games for this dip:
ECL 3 - Lose out on Battle Ardor and Uncanny Dodge, the factotum benefits should make you forget those though!
ECL 5 - Factotum 2/Wb 3 works really well! Miss only the bonus feat.
ECL 9 - Miss a bonus feat, but keep Imp. Uncanny Dodge, and Battle Cunning.

At higher ECL's you need to weigh any benefits of this dip against prestige class benefits you may be missing out on.



2. Four level dip
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What you gain:
Imp Reflex Saves.
3 Inspiration Points per encounter.
A utility 1st level spell or 2 (very minor)
Brains over Brawn - Get your int modifier to all str, dex checks and any skill check based on those skills. This could be EXTREMELY useful to a tripping or bull-rushing WB. Synergy with the Knockdown/Knockback feats is delightful.
Cunning Strike - Gives minor sneak attack, by RAW I think you can get 3d6 out of this once per encounter on a single attack.
Cunning Defense - 1 IP gives you int mod as a dodge bonus to AC against an opponent until the beginning of your next turn. Once per turn per foe. Useful for boss fights, or against ranged touch attacks if you don't have Wall of Blades prep'd.
Cunning Insight - For 1 IP and no action, add int mod to any attack roll, save, or damage roll as a competence bonus.
Cunning Knowledge - For 1 IP, get a +4 to any skill check.
Trapfinding.
A metric ton of extra skill points to spend on ANY(!!!) skill. Nice for giving that big guy with a sword a little perceptive ability, a little UMD ability, or whatever you need to fill out/assist party roles.

What you lose:
1 point of BAB, 2 IL, a handful of hp (d8 vs. d12) a point of fort save. 2 maneuvers known, and 2 maneuver retrains (depending on what your WB level is). Possibly a maneuver readied. Possibly a stance.

Good level games for this dip:
ECL 5 - This is a fun one. You come in with a ton of skills and can go straight for the 2nd level maneuvers with your first WB level.

Weigh other levels carefully against PRC entrance and long term benefit.



In a gestalt game, the WB//Factotum can be a very powerful primary melee'er.
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Man, oh man this is fun for gestalt. Keep an eye on the following levels:
Level 8 - You get Cunning Surge, this is fantastic, breaks WB action economy wide open. You can initiate a maneuver and make a full attack, initiate two maneuvers, or do a maneuver and recovery! Talk with your DM about whether or not this is usable multiple times a round. Avoid flying DMG's. If you have an ECL 8+ gestalt game, and you'd like to play a Warblade, strongly consider the factotum for nothing other than this ability.

If this is usable multiple times per round, you can take Font of Inspiration once (see below) to open every combat with WRT, Surge to recover maneuvers, Surge out WRT. Everyone in your party will thank you. Your DM will likely not. Even if you don't take Font, you can still use WRT, then on your next turn, recover maneuvers and surge out WRT!

Level 11 - Cunning Breach. Allows you to bypass SR/DR for 2 IP. This can be very broadly useful with your arcane dilettante ability. Or use it to punch the hell out of golems!

Level 16 - Imp Cunning Defense gives you permanent int mod as a dodge bonus to AC, have to be in light armor though. Major downside here if you aren't in a mithril breastplate or the moral equivalent. This can be much better if you're going for a more dextrous build to take advantage of two-weapon fighting.



Feats:
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Font of Inspiration, if it is allowed can be very tempting. Usually the WB has better things to do with its feats, but you could make an exception based on a couple of possibilities. The only time I would feel strongly about this is at Factotum 8.

If you're in a gestalt game and trying to nab Cunning Surge, you'll have 5 IP at level 8. Cunning Surge costs 3 IP to use. Taking Font of Inspiration once gives you 6 IP total and 2 uses of this ability. As you don't normally get your 6th IP until Factotum 11, this can be very profitable.




Mineral Warrior Template:
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Do you want the extra human feat and skills but also want sick racial advantages? For LA +1 you can have the mineral warrior.

Link to web excerpt:
http://www.wizards.com/default.asp?x=dnd/ex/20031003e

Disclaimer:
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First, mineral warrior is a very powerful +1 LA. You should probably ask it about explicitly if your DM is allowing +LA races. Especially at low levels, DR 8/Adamantine can be tough to deal with. This is obviously most effective in games where LA buyoff is allowed and you start at ECL 3+. Since mineral warrior penalizes int, I wouldn't try to combine it with the factotum dips above.


What you gain:
DR.
NA.
A burrow speed (usually 10-20 depending on race/class/dips)
Earth Strike (partially useless given your racial HD. 1/day gives you Con modifier to-hit).
Darkvision 60.
Bonuses to Str/Con, penalties to all mental stats.

This gives you incredible staying power. If you want to play a WB as a primary melee man, this template gives you a huge number of edges. At low levels, weapons that penetrate your DR are very uncommon, at higher levels, they aren't especially common, but your extra hp cushion, and thicker NA will still be very beneficial.

What you lose:
1 BAB (offset by str bonus), possibly +1 to a couple of saves (fort offset by con bonus), possibly a maneuver known, possibly a WB class feature depending on the starting/ending ECL.