One of the dealers at Dragoncon had a table full of D20 supplements and was selling 10 for 10 bucks. I found some by Atlas Games so I picked up all of those, then filled in the holes with some Fast Forward stuff and a couple of Sovereign Stone books.
Once I started reading them, I got really, REALLY inspired. The Atlas Games Penumbra materials were wonderfully written and rich. I just kept finding more and more ways to expand The Great Campaign In My Head(TM) and couldn't wait to read more. The other stuff I got wasn't so hot. I tried to read the terribly disjointed and poorly fleshed-out Dungeonworld book and a Living Arcanis city guide... but they sapped me and made me ill equipped to delve into the Soverign Stone stuff. In the end, I got the feeling that I was just lucky to grab the Atlas Games stuff... and so I started shopping for stuff on Ebay.
But once I got there, I found lots of odd lots running for less than a few dollars per product. It got me wondering if anyone out there is a fan of the third party D20 materials and which brands they respected. I can't stop raving about the quality of the Penumbra line.... so which did you care for?