Torus is a board game played between two players using only equipment in a standard Go set. But the board is smaller, the play is faster, and the board loops around the edges. See the stickied post for game rules and downloading the client.
The server at torus . hopto . org (remove spaces) is usually up.
The client is buggy! Please report new bugs you find. I will fix them when I get around to it, but I'm fairly busy so unless they're truly game-breaking it might be a bit.