Well, being the geek savant that he is, Jonathan Coulton covered Still Alive. Being the WoW culture savant that he is, Spiff took JoCo's cover and turned it into a World of Warcraft machinima. (There are plenty of references to the original Portal game in the video, though, so this version isn't entirely detached from its roots.)
Like all of Spiff's videos, Still Alive -- JoCo version is a lot of fun. Spiff does a great job capturing the fun and humor of JoCo's original music. Not to mention, his animation skills are constantly growing and always impressive.
Edit: JoCo wrote the original song, mind you. Still Alive was performed at the end of the game by a female artist. This song, then, is the version performed by JoCo. "Cover" is a tough word to use for this, so I wanted to clarify it.