Very cool project! I have used nearly every framework under the sun and React is, by far, my favorite. It's getting better every release. The concepts it introduces are sound, and I don't think I'd ever do frontend development any other way.

That said, Riot is a very encouraging take on React - and I think it may have a very solid place in apps that need to be very light and fast. Perhaps it's perfect for prototyping. I will try to find a small project for it.

One question; is there any way to render to a string so Riot can be used server-side?