Take a trip to Hoffer's Tropical Pets. It's simply amazing how big it is. 6 display tanks, 2 indoor ponds (one freshwater koi, one salt water tide-pool) and 1 alligator pit. It's not the cleanest, and the few plants they have aren't very healthy, but it is well worth the visit.
Oh, and there is a pretty active club down in Milwaukee as well. Here's a link:http://milwaukeeaquariumsociety.com/wp/