(I posted this in other thread recently)
How about these?
http://www.dragongoserver.net/
http://www.littlegolem.net/jsp/index.jsp
http://www.itsyourturn.com/
(it has GO among other games)
http://kgs.kiseido.com/
(this is a real-time GO server....but...If you set up a game with no time limits, it is possible for one of the players to move when the other is absent. So unlike other real-time servers, this one can be used for a non-real-time game. However both players must be present at once to get the game started.)
And the site of the Turn-based Go Guild is at this addresss:
http://finance.baylor.edu/rich/go/goguild.html
🙂