Just read this in the paper this morning, there's a bus company that travels around the midwest, with lots of stops, such as Chicago, Minneapolis, Detroit, Cleveland, Cincinnati, Pittsburg, Toledo etc.- seems like the base is around the Chicago area.
The tickets go from $1 (!) to about $45 - if you get it early, the fare will be cheaper.
It seems like a good way to travel around that area without a car, just drop into a city and take the bus when you're ready. They use online ticketing and sidewalk stops, so no terminal and no money onboard.
It's Megabus, run by Coach USA, so it's pretty safe, but might be a little squished and a teeny bit dirty :)- but so is camping right? Here's the link for the site.
They're planning to launch some more stops on April 2- such as Columbus, Kansas City, Louisville etc.
Think it might be a good alternative for the underage kids who can't get a rental car, but want to check out some cities.