Lava Lounge with worth checking out for the ambiance alone. Go to here, get a few drinks in you, and you will feel like you're in the cantina scene from Star Wars: A New Hope. For real. The decor looks amazingly like an underground lava bed. The crowd is pretty eclectic, too, which makes the typical South Side people watching and mingling so much more interesting.
The bottle selection is great and they play all 80s music on Friday nights! To put it in Yelp terms: Yay! I'm a fan.