Pickings are pretty slim right now. Of the games I've tried,
Proton Pulse was one of the most polished, though it's still somewhat simplistic. As for non-game experiences,
The Chair is a must-play.
It's true. Rift's aren't yet common, but tbh I was also hoping to see what people think of the Rift generally.
Now that I've played something decent on it, I appreciate it much more...
The game I played -
http://www.pocketgamer.co.uk/r/Virtual+Reality/Omega+Agent/news.asp?c=61751 - had some really simple graphics, and the physics model is just as simplistic, but the Rift somehow fills in a lot of gaps between your imagination and your perception of the game world.
That takes nothing away from the devco though, because the controls in this are on Nintendo's level.
Was a skeptic before, but now I'm very interested...