Cosmopolitan has knocked my socks off a lot lately, and the most recent reason being the free concerts they offer at Book & Stage.
If you go to Cosmopolitan's website, you can see a list of their regular concerts (which have included Smashing Pumpkins and Foster the People), guest DJ's at their clubs and lounges, and indie bands that play for free at Book & Stage. Make sure to check Cosmo's twitter page for last minute concerts or time changes.
I've been lucky enough to catch Robert Randolph and the Family Band as well as Grouplove here and really enjoyed both concerts. The acoustics aren't the greatest considering you're in a lounge but you can still hear everything perfectly fine. Look out for the tourist prices on alcohol at the bar.
Major hipster bonus points!