Top 5 D&D Books

[Odhanan]

Arcana Evolved
Unearthed Arcana (for 3.5)
Rules Cyclopedia
GAZ 1 - Grand Duchy of Karameikos
OD&D - White Box

That's really the choice of the moment : Forgotten Realms Campaign Setting, World's Largest Dungeon, Ravenloft, Temple of Elemental Evil, Tomb of Horrors are at the same level I think.

 

[MonsterMash]

For me:

City State of the Invincible Overlord
Tome of Horrors II
Players Guide to the Wilderlands
Conan RPG
The Grey Citadel

 

[der_kluge]

Magical Medieval Society: Western Europe
Artificer's Handbook
2nd edition Al-Qadim core rule book
Tome of Horrors
Planescape boxed set

 

[Odhanan]

Magical Medieval Society: Western Europe

Definitively an excellent ressource!

 

[solomoncane]

5 books

Besides the core books, pens, pencils, dice, and paper mentioned, I would choose:

Grim Tales
Unearthed Arcana
Arms and Armor 3.5
Second World Sourcebook
World's Largest Dungeon (I don't own this, but it is really big)

The original post specified D&D, but if d20 were generally considered, I may have to substitute the Traveller T20 Handbook for SWS.

(p.s. I really enjoy posts like these, because they help me consider what I really use and what I should liquidate).

 

[Squirrel Nutkin]

City State of the Invincible Overlord

Oh yeah. If we're allowed to include non-D&D products then I'd add this to my list and either lose the module or the Gazetteer.

 

[shilsen]

Seems like I've done this before:

d20 How to Make Oars out of Sand
World's Largest Inflatable Dungeons
Player's Guide to Edible Stuff Found on Desert Islands
Complete Wilderness Survival Kit (with Swiss Knife, Flares and 17-Course Dinner Insert)

and one non d20 book:
Complete works of Shakespeare or Terry Pratchett (I need something to read on the trip)

 

[KaosDevice]

Hmmmm...for me it would have to be:

The Babylon 5 d20 fact book, etc. (Main Rule Book)
Call of Cthulhu d20 (If I couldn't take my BRP gear)
Forgotten Realms Campaign Setting
WaterDeep Boxed Set (2E)
Ruins of Undermountain Boxed Set (2E)

 

[megamania]

Huuumm....

MM II
MM III
Darksun Campaign Book
Eberron Campaign Book
Ex Psionics Handbook

Play almost anything with those eight books, any style and any type of world.

 

[Evilhalfling]

Seems like I've done this before:

d20 How to Make Oars out of Sand
World's Largest Inflatable Dungeons
Player's Guide to Edible Stuff Found on Desert Islands
Complete Wilderness Survival Kit (with Swiss Knife, Flares and 17-Course Dinner Insert)

Just lovely

assuming the above titles were out of print.
Grim Tales
Worlds Largest Dungeon.
XPH
the Inner Planes (planescape)

no other players?
erm. BoEF