Creating your own online chess variants

Is there a place online where I can create my own variant and play it online with someone else?

Didn't try it but maybe it is something:

http://play.chessvariants.com/pbm/

Depending on what you want there are several ways to do play self-made Chess variants over the internet. One way is through a peer-to-peer connection, where the players connect directly to each other without a mediating server. E.g. if you and your opponnent both start WinBoard (or XBoard, if you are a Linux or Mac man) with the p2p adapter as engine, moves made on one end will show up at the other, and vice versa. You can configure things like board size and allowed piece moves with a small text file.

If you have access to a general webserver you can post your own server pages there, like I for instance did at http://hgm.nubati.net/variants/elven/ .

It also dependson how exotic your variant is. If you want 3-dimensional or hexagonal or circular boards life becomes a lot harder. If you want to move multiple pieces in one turn, ditto. But if you have a reasonably normal variant, with pieces that just move differently from the orthodox ones, and do not cause side effects on other squares, WinBoard should be able to handle it.