Themes Smartphone Apps - MobiHand Apps Store
I've found many, however I haven't found one I like more than the stock theme :-\ Give the developers some time to get used to 6.0 and I'm sure we'll see some pretty incredible stuff.
The only one I've liked so far is this one: (
http://www.mobihand.com/product.asp?...htc-Incredible ) but I switched back to stock because I can't live without the drop-down Today menu on the home screen. It's one my fave features of OS6!