"X3000 HD" (iPad) A fun, crazy horizontal side-scroller sci-fi space shoot'em up. They don't make them like this anymore!
"World of Goo" (iPad) This is one beautifully designed and executed game (physics-based puzzle). Superb art direction, animation and gameplay.
"MineCraft" (PC) This has a large cult following and the guy who wrote it has just sold his one millionth download, but I can't get into it and can't get past the really crummy graphics. See for yourself here