My favorite stuff:
1. Star Wars Revised Edition Manual- This game rocks my world. Best SWRPG ever made. The original d20 game was too flawed, IMHO, and the d6 game did some things better (Vehicle and Starship Combat) but absolutely sucked at others (Force Powers, Jedi, Power Scaling, Game Balance...)
2. Whell of Time RPG- HELL YES! My favorite fantasy world in playable form. The channeling system blew me away- it's the most intriguing magic system I've ever seen in an RPG (with the possible exception of Earthdawn's magic system, which, while interesting, was often far too complex for easy use).
3. Oriental Adventures- I love the elegance of this book- it is a relatively painless way of changing setting without totally rewriting the underlying D&D game. It goes far in showing how versatile even Core D&D (not necessarily d20) is.
4. Dragonstar Starfarer's Handbook- See #3, only this time think Space Fantasy or Pseudo-Cyberpunk (like Shadowrun). Useful for more than just the Dragonstar Setting, it's all you need to add high tech, vehicle combat, space travel, or other future weirdness to your D&D game.
5. Spells and Spellcraft- FFG knows how to make a good book. Their materials don't step on the toes of established WotC D&D rules, and are far superior (IMHO) to the softcover splatbooks that WotC has cranked out. Spells and Spellcraft provides a way to add interesting new dimensions to D&D magic WITHOUT unnecessary Prestige Classes or mechanics.
6. Spells and Magic- Bastion Press, on the other hand, presents a lode of alternate magic systems using prestige classes- and, unlike WotC, does them well.
7. Manual of the Planes- Planescape fans, take note. This book is the ticket back to those lands we know and love- and beyond.
8. Epic Level Handbook- It's crazy. It's cheesy. And it's a whole lotta fun.
9. Seafarer's Handbook- Like underwater adventures? (Sounds almost like a porn advertisement...) Like pirates? Like the age of exploration? Like airships? Get this book- it's your ticket to adventure.
10. The Forge of Fury- So far, my favorite 3e/d20 Adventure Module... but I still need to see Necropolis... and I'm eagerly awaiting WotC's new Drow adventure as well...
