Hey all. I've been away making one of these.. it's just opening.. so i'll add it to the list :)
http://kustomzone.com
It currently supports Flash/Html5 (1 file) drag n drop uploading..
My preference for C2 demos (due to technical reasons) is for a zipped game folder, and the assets not in any subfolders. The zip name is assumed to be the game name, and everything sandboxed within that game folder under a persons user account.
Let me know what you think. cheers!