I know that 'tis the season for bundles, but since it's also for charity, I figured that it's worth mentioning:
Wolfire is running another edition of the Humble Indie Bundle. Once again, you pay what you want and you get 5 games, with some money going to charity and some to the developers. You also control how the money is distributed, so you can give it all to charity or all to the developers or just split it. Last time they added a sixth game for free after you had paid - this time they've added all the games of the first bundle for anyone who pays over the average (currently $7.65). That last bit showed up as a nice surprise in my mailbox this morning (or maybe not, since I bought the first bundle as well, but still) and I haven't seen it mentioned anywhere else, so I figured I should spread the news.
For $7.65 (right now), you get Braid, Cortex Command, Machniarium, Osmos, Revenge of the Titans, World of Goo, Aquaria, Gish, Lugaru HD, Penumbra Overture and Samorost 2. IMO, 8 of these games are truly good, for different reasons, and are worth checking out.