So I'm looking to buy a ton of books...

[Pants]

Eberron Campaign Setting
Forgotten Realms Campaign Setting
Seriously, you don't need any more than these two books to run some long campaigns with.

For player's options stuff:
Dragon Compendium
Expanded Psionics Handbook
Draconomicon
Libris Mortis: The Book of the Undead
Arcana Evolved

Any of the 'Complete...' books will do, though 'Complete Psionic' will be pretty useless if you don't get XPH and 'Complete Divine' pretty much sucks.

 

[Aus_Snow]

'Complete Divine' pretty much sucks.

Ah, a good bit of derailing - that'll wake me up good and proper.

Which is to say, I've got more use out of Complete Divine than Compelte Arcane, personally (if only by a small margin). I really like some of the PrC's, and the Shugenja (aka Elementalist) has seen a fair bit of use so far. The Turn Undead rules variant is good (IMO), and the Divine Feats very useful. What can I say, I like this book, give or take a couple of things.


But more to the point, they've already got the 4 'complete's (all except CP).

 

[Nellisir]

Arcana Evolved, Mutants and Masterminds, Oriental Adventures, Stormwrack/Frostburn/Sandstorm, FRCS, Eberron, Manual of the Planes/Planar Handbook, Tome of Horrors I-III, Dawnforge/Age of Legend, Fiend Folio, Races of --

 

[Pants]

Ah, a good bit of derailing - that'll wake me up good and proper.

Which is to say, I've got more use out of Complete Divine than Compelte Arcane, personally (if only by a small margin). I really like some of the PrC's, and the Shugenja (aka Elementalist) has seen a fair bit of use so far. The Turn Undead rules variant is good (IMO), and the Divine Feats very useful. What can I say, I like this book, give or take a couple of things.

That seems to be the general consensus, but every time I flip through this book, I am never really 'inspired' by anything in the book.

OTOH, Complete Adventurer and Complete Arcane inspire me both as a player and a DM (though I kinda still prefer some of the material in Tome and Blood than the revised stuff in CA)

But more to the point, they've already got the 4 'complete's (all except CP).

That'll learn me to read!

 

[Greg K]

For d20 Modern
Blood and Fist (RPGObjects)
Blood and Blades (RPGObjects)
Blood and Spooks (RPGObjects)
Elements of Magic: Mythic Earth (ENWorld)
Psychic's Handbook (Green Ronin)


For DND
Unearthed Arcana (WOTC)
Stormwrack (WOTC)
Psychic's Handbook (Green Ronin)
Shaman's Handbook (Green Ronin)
Witch's Handbook (Green Ronin)
Experts (Skirmisher Press)
Wilds (Alderac Entertainment Group) and/or Wildcraft (Fantasy Flight Games)
Cityscape (Fantasy Flight Games)
Seafarer's Handbook (Fantasy Flight Games)
Traps and Treachery (Fantasy Flight Games0

Other
True20 (Green Ronin)
Mutants and Masterminds (Green Ronin)
Rokugan (Alderac Entertainment Group)

 

[Odhanan]

From WotC:
Unearthed Arcana
DMG II
Libris Mortis
Heroes of Battle
Fiend Folio (for Monsters)
Red Hand of Doom (as adventure)

Other d20 book:
Arcana Evolved
Iron Heroes (for options such as challenges and stunts usable with D&D, plus a host of other options you may consider as house rules, such as skill groups, feat masteries and such if you like to ticker with game mechanics, of course)
Shackled City Adventure Path (for a campaign)
Book of Fiends (from Green Ronin, just received that one and ... it's damn good for ideas of adventures based on fiends and particular demons, devils and daemons)
Complete Book of Eldrich Might (for Bard and Sorcerer variants, as well as spells, monsters and locales to use in your D&D game)
Other books of might: Books of Hallowed Might, Book of Roguish Luck
Advanced Player's Manual (Green Ronin) for various options
Wilderlands of High Fantasy boxed set and player's guide (for Campaign Setting)
Ptolus (for setting/campaigns)
City State of the Invincible Overlord (for another city setting)

Just a few ones coming to my mind, really. There is a lot of good stuff out there.

 

[Aus_Snow]

Good call on Unearthed Arcana! Doh, how on Earth did I miss that one? One of my favourite D&D books of all time. Yeesh.

 

[RisnDevil]

As far as player options go, the aforementioned Unearthed Arcana is a must. I would also recommend Savage Species. Magic of Incarnum would be good for more player options, along with the Psionics books. The Heroes books are good for both players and DMs. Personally, as a player, I REALLY liked Libris Mortis, and Draconomicon was pretty good too. Lords of Madness did not really do much for me as a player. Races of Dragon has the most to offer out of the races books, though they are all good. Weapons of Legacy is a fun player option book too.

 

[Ghostwind]

For players, I would recommend these for a good sampling of many different options:

* Mercenaries (AEG)
* Feats (AEG)
* Arms & Armor v3.5 (Bastion Press)
* Spells & Magic (Bastion Press)
* Dweomercraft: Familiars
* Path of ... series - 4 books (Fantasy Flight Games)
* True20 (Green Ronin)
* Thieves World Player's Manual (Green Ronin)
* Advanced Player's Manual (Green Ronin)
* The Black Company Campaign Setting (Green Ronin) - one book covers it all
* Kingdoms of Kalamar Player's Guide (Kenzer & Co.)
* Spellbound (Living Imagination)
* Arcana Evolved (Malhavoc)
* Complete Book of Eldritch Might (Malhavoc)
* Book of Iron Might (Malhavoc)
* Book of Roguish Luck (Malhavoc)
* Iron Heroes (Malhavoc)
* Conan RPG - Atlantean Edition (Mongoose)
* Ultimate Magic Items (Mongoose)
* Player's Guide to Arcanis (Paradigm Concepts)
* Dark Legacies Player's Guide (Red Spire Press)
* World of Warcraft RPG (Sword & Sorcery)
* A Game of Thrones RPG (Sword & Sorcery/Guardians of Order)
* Warcraft: Magic & Mayhem (Sword & Sorcery)
* World of Warcraft: More Magic and Mayhem (Sword & Sorcery)

 

[Mistwell]

"Races of" books (I am a particular fan of Races of Stone).

Unearthed Arcana

DMG II

Player's Guide to Faerun