AgoraNomic

Quoting the page http://www.dfw.net/~ccarroll/agora/ :

 Agora is the oldest known active nomic on the Internet--we 
 celebrated our 6th birthday in June 1999!  Agora itself was
 started following the collapse of another nomic, Nomic
 World, which was the first known MUD-based nomic.  Five of
 the participants of Nomic World are still Players in Agora
 to this day!  (Michael, Blob, Oerjan, Steve, and Chuck)