MudOS is a derivative of the LPMUD driver. It is more efficient and has a wide following amongst MUDders, but cannot compare to the following of a DikuMUD.

Lima is designed for use on the MudOS driver. TMI-2 is an old MUDlib, but is still (sadly) used for many projects.

Beek (Tim Hollebeek) was once the driving force behind MudOS, but has since retired. His spot has been taken over by Matt Messier, who has recently thrown in the gauntlet and decided to only do minor updates, after the supposed failure of his own MUD.