Aah Portal, Valve's puzzle video game which runs in a first-person/single-player mode. It was released together with Half Life 2 (B.G.E) and Team Fortress as a bundled package called the "The Orange Box", which just came out a few days ago for the Xbox 360 and PC. In the game, you play a character named Chell who is a test subject in a certain science facility. Your basically there to test out the "portal gun" in solving puzzles, for those of you who have no idea or have never heard of what I'm talking about, head on to the links below to try out a Flash-based game that shows what Portal is all about.
Further on through the game, in of the test chambers, you'll be introduced to the Weighted Companion Cube... you'll feel something for it... you'll do something to it...(I'll stop here with regards to the story because I don't want to spoil it for those who haven't played it yet) A person that goes by the alias Moony created this wondeful cube. Thanks!
Weighted Companion Cube [via Mediafire]