I first heard of the first one from a post here...and it was great. I highly reccomend these game bundles. Braid and Osmos alone are great. I still have to check out the others.
http://www.humblebundle.com/Here's the blurb...
Pay-what-you-want for five awesome DRM-free games on Mac, Windows, and Linux: Braid, Machinarium, Osmos, Cortex Command, and Revenge of the Titans. Choose to support the Electronic Frontier Foundation and the Child's Play Charity at the same time.
If you haven't heard of Revenge of the Titans before, it's because it is being launched directly into the bundle. Also, Braid and Cortex Command are available on Linux for the first time inside of the bundle. The bundle comes equipped with two soundtracks and one mini-album for Machinarium, Osmos, and Revenge of the Titans.