Aside from my DMs clause of:
Every race/template/class/feat/equipment/spell/power/soulmeld/utterance/vestige/mystery/magic item etc must be submitted for approval. I usually allow right off the bat the entire Complete Series, Races of Series, Unearthed Arcana, and the Monster series.
Any alternate systems (psionics etc), Heroes of, Environment series, Creature books (Draconomicon etc), Manual of the Planes/Planar Handbook, Oriental Adventures etc are all campaign specific.
As my current campaign is a Planescape one, the players, and myself (the DM), pretty much have access to everything.