In the bands I play / have played in myspace has been a great tool. Great for posting shows / new songs / news. Quick and easy way to get feedback too. After every show we play we usually get a bunch of friends requests as well as people posting "Great job last night" or some other compliment. People will even send links for photos or videos they've taken at the shows.
Guitarist / vocalist of one band takes myspace really seriously and spends entirely too much time on it. He will go to pages of bands in the same genre and add people commenting on their page with personalized messages asking them to check out the songs and post a comment with their thoughts... Nerdy / goofy as hell but it works.
Bulletins are a great tool, but the quickest way to piss people off is to post bulletins constantly. I've removed people from my friends listing on my personal account for bulletin spamming.