This one is courtesy of Steam.  I've been looking to pick up this game anyways since the news of the sequel hit the street, and this just made my purchase that much easier.  A current generation title for $5?  Yes, please.  If your machine can run it this is an awesome deal.  Even if you're not really interested in the game it's worth a shot at this price.  I found out about this from my boys at Joystiq:

http://www.joystiq.com/2009/02/27/steam-weekend-special-lost-planet-for-5/

And here's the Lost Planet 2 trailer announced earlier in the week: