The last part of my general Core fix is fixing the rogue.

Rogues are interesting, in that they are both a bit underpowered (in combat) and overpowered (in that it is too easy to use skills, particularly Diplomacy, to the point of brokenness). Therefore, this is both a nerf and a boost:

The boost (based on suggestions by NeoSeraphi):

The rogue adds the following to the list of available special abilities gained at level 10 and every 3 levels afterward:
-Expanded Sneak Attack (Ex): The rogue may sneak attack from up to 60 feet away (rather than the usual 30).
-Hide in Plain Sight (Ex): The rogue can use the Hide skill even while being observed. This requires a move action, and the Hide check is made at a -10 penalty. The rogue likewise only takes a -10 penalty to her hide check (rather than the normal -20) when sniping. In addition, the rogue can hide without cover or concealment, but takes a -10 penalty (which stacks with all others) to the Hide check when doing so.

The nerf:

-(Inspired by the Giant's fix to Diplomacy) When using the Diplomacy skill to change an individual's opinion, the DC to improve the target's attitude is increased by the target's hit dice plus his wisdom modifier. This increase is not applied to the DC to avoid lowering the target's opinion. The increase also does not apply to Diplomacy checks used for purposes other than changing an individual's attitude, although DM-required Diplomacy checks to persuade someone to do something may have such an adjustment included in the DC.
-An item cannot give a bonus to a skill greater than +15 (rather than the +30 of RAW.)
-Items boosting skills involving social interaction are assumed to compensate for the result of the target being aware of the item, and therefore are capped at a +5 boost. It is possible to make an item that does not compensate for such, and thus is both half price and can give up to a +15 boost, but if the target is aware of, or even suspects, the item and its purpose it fails to work and creates a -5 suspicion modifier to the check.

Note that the nerf is not meant to make skill use useless, or even unbreakable. It is, however, meant to make them roughly as possible to break as they are in real life.