I've used Steam's big picture mode to play GTA SA, and it looks so much better on my tv. right now it's the only game that works right since it's one of the few I have thats compatible with a ps3 contoller.
finally. GTA with mods on a tv...
So, I think it's a pretty cool feature.
with that said, who else use's steam for this? does it work well for you? if so, what games work best with it?