Our good friend John Skarha has been running indoor winter games for the past few years. We'll be back at Westmont Yard this year (a pretty nice facility, actually).
Due to fields costing money, playing here will cost you $10 each time. If you're not a fan of the cold, it's a pretty good way to keep the rust off during the colder months.
Games go from 9 PM - 11 PM, with typical post-game food at Roundhead's (a bar that has pretty terrible pizza/food, but it's close and open).
The group also has an outdoor game that (unfortunately) clashes with ours day/time-wise, but they're in Wheaton, which might be closer for some people some times. Check the site out here - http://sports.groups.yahoo.com/group/SPUNultimate/