The 1800 club is basically an undergrad hangout, people go occasionally but not often. The Keg is the late night Tuesday night place. Personally I love Bat 17, so many amazing sandwiches there and their brunch is the best in town. Steel's list has most of the places I was going to add but in addition to those Koi is good, Tapas Barcelona, and Red Mango (frozen yogurt) are great.
Insider food times. Tuesday is $1 burger at Bar Louie, not the greatest but they are a dollar and then $0.50 for each topping, and veggie burgers are $2. Students get pizza's at whole foods for $9 every day, cheapest pizza you will find and they are good.
There are lots of different things people do for fun. I usually go to Champps in Skokie to watch UFC fights with friends every month or so, food isnt great but its always a good time. People also go to Chicago for dinners, its pretty easy to get in and out of the city. The only issue is food gets expensive downtown, especially at the steak houses and stuff like that.