Potato is a MUSH/MU* Client for Microsoft Windows and Linux. It's small, but has a rich feature-set, and works almost identically across both operating systems.

Potato supports all the standard features you'd expect from a MU* client, like the ability to store and connect to multiple worlds, ANSI colors and basic telnet support. It also has many more advanced features, like highlights and triggers, timers, Unicode support, spawn windows, and much more. And it runs on Windows (2000/XP/Vista) and Linux. (Support for MacOS X is planned, eventually; follow the link for more info.)

The latest version available to download is 2.0.0.b2 (minor bugfixes/new features).