I've been enjoying the puzzle game Subway Shuffle on my iPhone. It's has a clean, simple design, is easy to play and challenging, plus I love this sort of abstract puzzle. (There's also a Mac trial version but no PC version).
The author, Bob Hearn, was a student at MIT, and it looks like this game was part of his Ph.D. research. (No, I haven't read his dissertation :P)
An unexpected discovery by way of the Subway Shuffle website is Robert Brinkerhoff - a talented artist who has an interesting blog covering art and life as an American in Rome.