2.1 is still in beta, but could we get a theme index going? I've noticed a few people working on some but it's not easy to track them down.
( http://custom.simplemachines.org/themes/ doesn't have the 2.1 themes option yet.)
i really doubt there are many people working on themes for 2.1 as it is still in beta. the theme site will most likely not accept themes until RC is reached.
Speaking as a theme creator also core worker on Curve2 (Default theme of SMF2.1) changes are breaking themes badly (time to time), so even you find theme(s) for SMF 2.1 they may be broken or not really functional :)
As already noted in several of the themes designed for beta 1--- they are pretty much completely broken by beta 2