Goto Big Star. It's awesome. My friend works at Groupon, and they just published her article on it today:
http://www.groupon.com/local/chicago...da-at-big-star
Also, Bub City, The Bad Apple, Longman and Eagle, Violet Hour, Bangers and Lace are all a lot of fun/good food/drinks. I'd mention more but those are all awesome.