Neat thread.
My D&D shelves look like this (from left to right):
- Core books and supplements -- PHB, DMG, PsiHB, other general rules
- Player-oriented books -- splats, CW, CD, etc.
- Forgotten Realms, including 2e material
Next shelf over:
- Monster books (loads of them!)
- DM-oriented books and campaign tools (Dungeon Craft, Book of Challenges)
- Secondary sources -- usefull books that aren't the best of the best (Spells & Spellcraft, for example)
- Adventures
One shelf down:
- Campaign setting stuff I don't use (Scarred Lands, et al)
- 3.0 core books (the main 3)
- So-so and mediocre material (Arms & Armor, Deities & Demigods...)
So far, it's worked for me. I've changed things around as certain sections -- like FR and monster books -- have overflowed their original spots.