Crayon Physics
I'm not a habitual gamer (so this is new to me), but I just played the most innovative video game since Super Mario Bros. and it wasn't on the Wii or playstation... it was on the iPhone.
For me, the best games are not due to graphics or technical sophistication but how it interacts with the player. Most games get boring really quickly because you're constrained by how much you can manipulate the virtual environment. Here, your goal is to make a ball hit a star by drawing shapes such as rocks to hit it or catapults to sling it or buckets and ropes or seesaws to manipulate the ball toward the star. This game and others, with the same idea, have been available for other platforms prior to me discovering it.
Here's a video of Crayon Physics Deluxe a few days ago on Gizmodo:
The magic is the way it makes you feel like you can control every part of the game and change the way you want to solve each puzzle. There's also a level builder so you can build your own puzzle. Rare is a game that allows you to feel there are endless possibilities. You can spend hours build seesaws, swinging clubs, bucket and rope, etc. $5 on the iphone and $20 on the pc I believe.
The only hiccup is that you have to have firmware 2.2 to download the game and you have to restart the iphone after downloading; otherwise, it keeps telling you that you have to erase something before drawing more shapes. After the reset, it worked flawlessly.
Thanks to Petri Purho and Hudson for making it available. Petri was also trying to make a game a week and there are a lot of interesting ideas and small game downloads on his site.