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.