I just like this tune so much I had to toy around with it myself a little: I took the two official versions of Still Alive, the theme of Valve's fantastic Game "Portal" - one sung by the game character GlaDOS and the other one by composer and writer Jonathan Coulton himself and mixed them together into a duet. While it's not perfect I think it's still pretty cool - enjoy!
Ok, usually I just post movies, but this time I need to send a warning ahead: If you, in the future, plan to play the game Portal and don't like spoilers, then don't read on and skip the movie - you'll be seeing it anyways... Oh, and don't read the explanation too...
These are the end credits of Portal which basically blew me away (see below):
Portal is a 3d ego puzzle game. Using the perspective every shooterfan will recognize at once (actually using the fine Halflife 2 graphics engine) it manages to be really tense and at times rather scary without any spacemutants out to eat your guts, guns and crowbars...