There's a YouTube video of the credits crawl, which has the Jonathan Coulton song. There are spoilers, so it's below the cut. If you're into Jonathan Coulton, but don't plan to play the game, I encourage you to check it out. If you do plan to play the game, probably don't.
Ok, so some context (which are spoilers, I warned you!) - In the game, you're part of a test program administered by a neurotic computer. (You remember "Electric Dreams", right? A computer falls in love with Virginia Madsen playing cello? Same idea, sort of.) At the end of the game (I'm really spoiling it now, stop reading!) you take parts of the computer and throw them into an incinerator.
Oh, and the test seems to have to do with using "portals" (hence the name) - you get a "neat gun" that allows you to determine where the ends of a wormhole (sort of) are - you can put them on floors, walls, ceilings, at will. Pretty much. So, the gameplay's not terribly violent - it's more of a puzzle game - I need to get from here to there, where do I place the portals to afford me access to the button I need to press?
With that, HERE is the YouTube link to the end credits song. You can't really read the crawl on the left - those are the lyrics. I've transcribed them HERE, if you like. The crawl in the upper right is the actual credits, in alphabetical order. Everything's done in a neat fixed-width console display, so the stuff that looks like ASCII art in the lower right is actually ASCII art.
Oh, also, the computer promised you cake if you finished the tests. I totally want cake now.