Seconded the suggestion of IdeaBounce. There's actually a fair amount of entrepreneurial spirit at WashU, though a lot tends to be in the biomedical area. While I wasn't a WashU student (ex-fiance was), I participated in IdeaBounce for a while and eventually networked my way into several other groups in St. Louis that were doing interesting things.
Beyond that, I had a similar experience as a student at Iowa State. Smallish town, a lot of folks focused on getting jobs, and the general creativity of the entrepreneurial groups a bit lacking. Eventually I made my way through to various programs about start-ups run by the state of Iowa and met a number of angels, early stage investors purely to meet other people doing interesting things (which landed me time doing sales at a photovoltaics company and business planning for a textbook coop idea). Really my goal was to meet a lot of people and learn a lot of things such that, when I moved out of Iowa (I'm in SF now), I felt like I made the most of the opportunity in the time I spent there.
In the end, I think if you try to be open and meet a lot of people, you'll eventually find others that share your interest and match well. Use STL as a place to hone your skills, toss ideas off people, and prepare yourself for opportunities in the future. Perhaps something will stick between now and graduation but, if it doesn't, you'll have learned a lot.