Are there any fun tours in Chicago that are more interesting than the usual architecture-type stuff?

I haven't gone on this yet, but I'm trying to talk my girlfriend into checking it out with me. Chicago is pretty well known for the criminals in the 1940s and 50s. We had a lot of gangsters like Al Capone, so Chicago Crime Tours are actually really a neat idea, and a great way to see the city from a different point of view. I saw one of the buses for the tour a few weeks back and it looked really cool. You can read more about it here: http://www.chicagocrimetours.com/