Whether it's cleaner rules or something that helps close the gap between martials and casters, give me your list.
Here's some of mine.
Vecna (Paizo doesn't have a deity that can compare with the big V! I mean he's like the Dr Doom of D&D, though he would bow before Doom!)
Reshar (Bo9s fame! The guy is bad@$$! Talk about a guy who's mythic and could take down mythic casters. I can only imagine his personal maneuver set.)
Let's just say overall fluff. A lifetime's worth.
Darkstalker ("Nuff Said")
Maneuvers, Soulmelds, Psionics, Inspiration points, Invocations, Vestiges, (All excellent sub systems that helps characters be less cookie cutter.)
Some excellent prestige classes. (For all your dipping needs!)
Dragon & Dungeon magazine. (Chock-full of wholesome goodness.)
How the d&d 3.5 FAQ handled the use of armor spikes (Suck it! ;-)
Adiós.