Besides the 3 core books, which sourcebooks/rules are you using in your campaign?

[Cheerio]

Outside the Core books I don't use (and likely never will) any additional books.

 

[Zarrock God of Evil]

Hmm. I've bought a ton of books but not quite gotten to use as many of them as I would have liked. I've used all the FR books and the RttToEE for my ongoing FR campaign. The splat-books are always at the table and my players always have access to them during character creation much the same goes for the PsiH. I've used the MotP for some private projects of mine (not yet directly used in a session).
Otherwise, I've used Traps and Treachery, Starfarer's Handbook, and Relics and Rituals quite a bit. I still haven't gotten to use my other d20 stuff but I'm sure an occassion will arise soon enough.

-Zarrock

 

[Krug]

I bought Defenders of the Faith and Sword and Fist and stopped there. Should I really fork out US$20 for the 2-3 feats or 3-4 spells I might actually use from the other books? Most of the PrCs aren't very usable either.

 

[Dinkeldog]

Krug, if any of your players are running those classes, Masters of the Wild is excellent.

I use:
All of the classbooks. Like Psion said above, Sword and Fist seems to be the most used, followed by Masters of the Wild (probably surpassed by me, since I've got a Druid character).
Psionics Handbook
Manual of the Planes
Forgotten Realms CS
Magic of Faerun
Monsters of Faerun
Oriental Adventures
Creatures of Rokugan
Rokugan CS

Non-WotC:
Heroes of High Favor: Dwarves
Traps and Treachery
Legions of Hell

Used and Discarded:
Relics and Rituals

 

[mkletch]

Mostly 'official' stuff

For my campaign, we use

Sword and Fist
Defenders of the Faith
Tome and Blood
Song and Silence
Masters of the Wild
Stronghold Builder's Guidebook
Manual of the Planes
Psionic Handbook (psionics different ; powers for traps, and creatures mostly)
Deities and Demigods (but very little)
Relics and Rituals I (spells & items only)
Creature Collection I
FRCS
Magic of Faerun
Monsters of Faerun
Book of Eldrich Might
Spells and Magic (spells and items only)

Basically, anything 'official', with some other bits used by the DM (i.e. me) for surprises.

Fletch!

 

[KDLadage]

Well...

• Core Three (PH, DMG, MM)
• Jagged Edge Games (V1, V2, V3, notes...)
• Wizards of the Coast (Class Books)
• Sword and Sorcery Studios (CCI, CCII, RR)
• Legends and Lairs (TT, SS, SHB)

That is about it.

 

[drakhe]

system wise I use the 3 core books
flavor wise I pick stuff up from about anything out there (+ novels, magazines, movies, internet, ;-) )

 

[bwgwl]

for the next time i DM 3e:

the 5 class books from WOTC (no prestige classes; only feats and spells)
MotP (only some of the monsters and templates)
OA (samurai and shaman only; some spells, feats, and monsters)
FRCS and Magic of Faerun (spells and feats only)
Seas of Blood
stuff here and there from Dragon Magazine (mostly new monsters and a few feats and spells)
jury is still out on the KoK Player's Guide

though 95% of the campaign is the core 3.

 

[Kanegrundar]

Here's my list:

Psionics HB
FRCS (races, ECL's, and a couple PrC's)
Mythic Races
Sword and Fist
Defenders of the Faith
Tome and Blood
Song and Silence
Masters of the Wild
Relics and Rituals (a few PrC's and spells)
Monsters of Faerun
Creature Collection (1 and 2)
Armies of the Abyss
Legions of Hell
Ravenloft CS (for the added rules for Vamps, Ghosts, Liches, and Constructs)
Ravenloft Denizens of Darkness
Manual of the Planes
Oriental Adventures (races, classes, PrC's, spells, monsters)
Monster
Minions: Fearsome Foes
Dragon Lords of Melnibone (monsters)
Diablo 2 (both Diablerie and To Hell and Back for a few monsters)
Enemies and Allies
Lords of Darkness
Magic of Faerun
Hallowfaust (monsters)
Vigil Watch (monsters)
The Wise and the Wicked
Call of Cthulhu (monsters, and soon for sanity rules...maybe)
Dragon Magazine

Yeesh! That never seemed like all that much before!

Adios,
Kiser

 

[Erik Mona]

It's nice to see so many of you using Armies of the Abyss! I had a blast writing it, and now that Morrus is selling them for under ten bucks, hopefully evil will spread far and wide.

--Erik