Lame MUD is planned to be an engine for virtual text based worlds (as opposed to the seizure inducing modern ARPG/MMORPG titles).
Currently, it's still in pre-alpha. The sources available for download are not even remotely resembling anything like a MUD. There is a network layer established and the server acts as a one room chat server.
A multiplayer RPG that connects as a psuedo server to an IRCD. Built in the tradition of old BBS Door games such as LORD (http://en.wikipedia.org/wiki/Legend_of_the_Red_Dragon). Forest fights add experience and gold needed to best your master (gain level
A modern mud-server. UnsignedByte uses a sqlite3 database as it's backend instead of slow and old-fashioned text-files. It uses a 3rd party GPLed socket library. Mugglenet's mud (Legilimensia) will use this engine when the project reaches beta stage.
Dark Beginnings is a MUD server made in C++ using Qt4.3 and MySQL, it is aiming at having a higher number of stock deployment options by use of scripted modules. Anyone is free to join and help out.
cppmudd is a small, fast and portable mud driver written entirely in C++ using either standard or widely available libraries (such as the STL). It provides, among other features, support for runtime modifications to the game, ensuring minimal downtime.
A complete cleanup (for readability and ease of coding) and doccumentation of the original SMAUG 1.4a codebase, SLAM-GTP is also a minor re-write, bringing new features to the codebase, while also fixing and/or adding functionality to existing ones.