Some of the mega corps do have some really cool work going on. It's not all rank-and-file development, I'm not even talking about R&D. The cities are fairly small compared to other larger midwest cities and if you have a decent reputation as someone who can deliver code or pick up good work there is plenty of opportunity to shine very brightly at a large org and have your pick of projects to tackle.
Fortune 500 aside, there are a lot of smaller startups in the cities. They mostly focus on creating products aimed at the health insurance industry though, which in my experience is fairly dull work.