oh right I should log into my LambdaMOO account to check what's up, it's been a long time
telnet lambda.moo.mud.org 8888
learned to program on that thing
LambdaMOO is mostly people being idle. There is, however, a spiritual successor called ChatMUD. It's based on a fork of a fork of the original LambdaMOO server called ToastStunt (forked from Stunt). It seems to have a bit more pep in its step if you're looking for a semi-active social / programming MOO.