Stop what you are doing. Stop reading, and go download the Echochrome demo on PS3. The game is full of the "i" word. It is just like Portal without the guns. You know what, it is really nothing like Portal. That is the point. It is like nothing else out there and it is addictive.
I read an article once where the author wondered what Escher would have done if he had access to computers. He would have built Echochrome. You know you had an Escher poster on your wall once. Go play.