The Shoujo-ai MUSH is really a great place to be. The story is just simple: An island somewhere, where the water has been cursed, so that only females can exist on it. It's basically a place to hang out and enjoy yourself.
It's, to my knowledge, the only MUSH which uses this system. (If someone knows of another MUSH which does not use a battle system, please contact me?)
All races are welcome, although Catgirls seem the dominant species on the island.
There is lots of love on the island and there are even weddings.
Offcourse, the theme of this MUSH (Shoujo-ai = Lesbian Relationship) requires players to be over 18, but that's understandable.
I've been registered there myself since June 2003 and I'm still enjoying it.