Everybody should see the Yeah Yeah Yeah's. They'll probably debut some new shit, and their live show is energetic and really fun.
If you like indie/folk rock, check out Fleet Foxes and/or Okkervil River.
If you're looking for weird trippy shit.. well it's all over the lineup really, but I'd recommend Gang Gang Dance.
Some fun DJ's - Felix Da Housecat was great in '07, and Girl Talk should be pretty fun too.