LA MUD is a text-based multi-user dungeon version of Los Angeles, currently in development.
Large portions of the MUD will be based on the LA-MOO project created by Jason Brown and Eddo Stern in 2003, and written by a vast array of collaborators.
LA MUD is currently semi-functional, but you might as well give it a shot. It requires a telnet client or a dedicated MUD client.
For more information, and to see if LA MUD is currently live: