there's the SLUniverse Members group in
SL, but the only way for us to post events is here. I have a few groups that I post the same events too, but if that's too spammy a suggestion, the alternative is to just keep checking here. There's a few geisha groups also, and you can even become one, if you so desired.
Arakawa Hanamachi and Pondlife entertainers are really good. They are some of the nicest people to work with.