CMUD/zMUD
Are you tired of the constant grind of the graphical MMO games? Tired of paying monthly subscription fees? Try playing one of the hundreds of free text-based adventure games on the Internet using CMUD: The fastest and most versatile MUD client from the creator of zMUD.
TinTin++
TinTin++, aka tt++, is a free MUD client for Mac OS X, Linux, and Windows. The Windows port named WinTin++ (using the PuTTY derived mintty terminal) is available for those who do not use Cygwin (A Linux/Unix emulator for Windows) and runs on Windows Xp, Windows Vista, and Windows 7. Besides MUDs, TinTin++ also works well with MUSH, Rogue, BBS, and Linux servers.
FMud - Play it in your browser!
Created by: Matt Adcock - FMud is a web based Flash MUD client which can be used by MUD owners on their websites to allow their players to connect to their games.