System Reference Document has all the rules, tables, spell descriptions; heaps of info. Also check out this one.

Characters with Class has some great overviews of character classes, strengths, weaknesses, what to think about when playing, etc.

Cyrstal Keep is a good page for spell lists.

Errant Dreams is a top place for all sorts of RPG info, especially the pages geared towards character creation. Really good ideas to flesh out your character and have some fun with it.