One of the first, if not THE first non-combat-oriented social MUD. Appeared at CMU in 1988(?)... Fuzzy and 4201 were very important to it. We also saw the first incarnations of Julia and Gloria the Maas-Neotek bots there!
Unlike more recent MU* servers, the original TinyMUD did not have any facility for destroying an object in its database once it had been created. This led to a structure much like the original Everything database :)