Star Conquest is a moo that I happen to think is quite nice. You can telenet to it at telnet://moo.squidsoft.net:7777 or you can use any mud, moo, muck, or mush client you happen to have
Its set in the future, where you assume the role of one of the pilots in 1 of the 4 alliances. Theres a good deal of socialising, and also a variety of way to get credits, the currency of the game, and points, which you need in order to buy certain things such as better spaceships. Speaking of ships, the piloting and space combat system is, in my opinion, very good.
So, if your looking for a futuristic moo, I'd greatly suggest this one.