The best of....?

[Keeper of Secrets]

Things I liked:

Iron Kingdoms Character Guide and Eberron for campaigns
Libris Mortis for suppliamental material
Foes of Freedom for best 'monster' book (a Mutants & Masterminds product)
Paranoia for best non d20.

 

[Mustrum_Ridcully]

From the book I "experienced" personally (either by buying or playing with it):
Legacy of The Dragons. It is a great monsterbook, full of creative ideas and plot hooks on how to use the monsters in a campaign...

Eberron. I really like the setting and enjoy playing in it...

 

[Flyspeck23]

Sharn, City of Towers - simply for the fact that it illustrated pretty well that WotC doesn't need to fill their books with "crunch only".

Product I resisted buying until recently that I really like: Complete Spell Cards. We have a great printer at work that can print on both sides of cardstock. The cards print beautifully and it really did speed the game up for me.

The Complete Spell Cards had been published in 2003, though. But they've been the most successful PDF at RPGNow.com in 2004. So next time, don't resist for that long

Anyway, glad you like them