Recently Evil Hat Productions put together a pdf bundle deal featuring Spirit of the Century, a FateRPG-based pulp super game, and Diaspora, a FateRPG-based hard science fiction game. Here's the link to this cool deal.
I really like the ideas found in the FateRPG, even though they're not a good match up to my regular gaming group's tastes. Along with zero-centric FUDGE dice mechanics, the concept of Aspects has probably done more to change how I think about games in the last five years than anything else I've read. If you're at all curious about the FateRPG, this deal is a great way to see two implementations of the system. If you want to find out more about the FateRPG itself, there are free downloadable copies of FateRPG 2.0 and the Spirit of the Century SRD on the main FateRPG site.
If you're interested in print versions of either game, they're a bit more costly, but you can get Diaspora here via Lulu, and Spirit of the Century here via Evil Hat's storefront.