I wrote this a couple of months ago, as it seemed like an interesting little side project. It's a really simple MUSH - Multi-User Shared Halucination / text-based roleplaying server.

FEATURES:
dynamic multi-level maps
customisable user permissions
user created content (objects and map areas)
interactive objects
multi-channel communication

Unlike most others, it doesn't require a database... all the characters/objects/locations/channels are stored in plain text files, and the server-client communication is done with basic posix file io. The result is lower memory usage than shared memory that some mush servers use, and without the overhead of a database server.

Plus plain text is human readable, and just awesome.

For those who are interested, you can get it here: wMUSH 0.1 Download