AL Client is a completely free MUD client for Windows, which includes almost all of the features of a pay client, including a mapping utility, automapper, edit box, hotkeys and customisable buttons.
Homepage for the free Pueblo MUD client for Windows computers originally developed by Chaco Communications in 1996. Chaco Communications no longer exists but the Mozdev community is keeping it alive.
Pueblo/UE is a multimedia MUD/MUSH/MOO/MUX (MU*) client for Windows 95, 98, NT, ME, 2000, and XP. Pueblo/UE itself is a recompiled and reconfigured version based on the source release of Pueblo 2.02 by Chaco Communications. This new version is maintained by Ultra Enterprises.
SimpleMU is a client for all MUD type games including MUSH, MOO, MUCK and MUSE. SimpleMU runs on Windows® 95, Windows 98, Windows 2000, Windows NT and Windows XP Operating Systems.
An alternative to the GUIs normally associated with Windows, TinyFugue for Windows is a port of the popular TinyFugue for *nix. A pretty powerful client, with triggers, logging and more.
Xpertmud is an extensible perl and python scriptable MUD client. It is based on Qt and KDE. There's a native Linux/KDE version as well as a native Windows/Win32 build. This enables you to use the same script on your Linux box at home and on your Windows box at work...