What we used last session
Group 1:
PHBK 3.5, DMG 3.5, MM1, Creatures of Rokugan, Rokugan, Oriental Adventures,
OA6 Ronin Challenge (adventure, 2e), Jade Dragons and Hungry Ghosts, Psionics Handbook 3.0, Tome of Horrors.
Next session:
Not sure, probably starting Rattan Appuk or going Spelljamming
Group 2:
Wotc:
PHBK, DMG, MM 3.5, MM2, Fiend Folio, Book of Vile Darkness, Book of Exalted Deeds, Unearthed Arcana, Complete Warrior, several articles from the Wotc website, Psionics Handbook 3.0, several dragon magazines, Magic of Faerun, Monsters of Faerun
(will need to toss in Epic level Handbook, Races of Faerun, and Al-Qadim 2.e/Land of Fate boxed set for the next session)
Green Ronin: Book of Fiends
Necromancer Games: Tome of Horrors
AEG: Creatures of Rokugan, Evil, Dungeons
(on a related topic; High level dungeons dungeons filled with Demons, Daemons, and Devils is both fun and rather resource intensive)