Vallheru is a turn-based, fantasy MMORPG written in PHP and MySQL (but may work with many other databases) with Smarty Template Engine, ADOdb, and PHP Mailer. It is based on Gamers-Fusion 2.5 with many modifications in security, speed, and features. It is currently available only in Polish.
KMuddy is a MUD client powered by KDE. It aims to be the most powerful, fast, feature-rich and easy to use MUD client. The current version already offers many features such as powerful external scripting (which supports very many languages such as Python, Perl, Lua, and C/C++) and its own internal scripting. It has split-screen scrolling, command history, an auto-mapper, buttons, gauges, logging (both in plain text and HTML), multiple connections, regex support (on both aliases and triggers), and much more.