MUDs

The term "MUD" comes from "Multi-User Dungeons"... but they're far more than that.

There are thousands of these MUDs online. Most of them are boring little holes where a few players have gotten together with a few ideas, but have no real programming experience. These little startup muds have nothing really exceptional to see or do, they're considered "Stock" muds, (basically only consisting of the pack-in areas and monsters and stuff that comes with the base code of the Mud) There are far too many of these.

A few MUDs have stood out, in my search for places to play. Alliances (previously Another World 1, then 2.) was the first MUD I really enjoyed playing. I've been involved in giving ideas to improve the world, and I have had an active participation in building the world (not so much building on Alliances, because of a few problems I ran into, in editing areas online.)

ALLIANCES

This could be a really neat MUD, focusing on the interaction between the 20+ races of the world, where players actions can change the world scene.
There's a lot of unique stuff planned... if anyone would actually work on it.
telnet to: mud.alliances.org port 4000