Bebo was for eurotrash. It's not really used anymore.
Facebook is okay if you're trying to cyberstalk a bitch. Twitter is just useless unless you're reporting a huge event that's going on and no tv crew is near by.
I use Facebook, but I don't really care for the others. I don't really give a shit what celebrities are doing, what they're eating, etc. Seems like a load of shit to me. Not familiar with Bebo, but I'll take Hiplop's word for it.
Don't use Facebook or Bebo, but Twitter can be entertaining if it's someone like Kevin Nash's or 50 Cent giving some stripper abuse.
Don't have one of my own and have no intention of getting one, plus I barely know how to work the thing (I'm 76 years old), but yeah, Twitter's a way for me to kill 15 minutes, like, once a month or something.