Since I'm in Columbus, I'm probably supposed to say that there are no cool places in Ann Arbor. :-)
But the way to find the start ups is to go to the local tech scene meetings: Perl, Ruby, Python, Node.js, big data. Check meetup, etc. Find a few meetings, go and meet people. Make acquaintances, and before you know it, sombosy will be coming over to you to say something like "Hey manglav, didn;t you say you were really good at technology X? Wanna consult for a couple of hours?"