OK I found a very interesting post on one of the other forums. Its not a game variant but more of a server variant.
http://www.rpgcodex.net/phpBB/viewto...ac020263fdc1c0
It explains how to do a PbEM style Dom3 game on anyones server, but using a file share site such as DropBox.
Like I said, not a game variant but it seemed worth posting here.