topmudsites.com From what i can tell the new big mud listings sites has sites of all the popular muds up today
www.zuggsoft.com/ Home of one of the greatest muud clients avaliable
http://mudverse.com/ One of the newer mud listing sites, List muds that are currently online
http://www.mudbytes.net/ Another mud community site. listing the current muds on the net
Mud Connector Once a great resorce for mud information.