Right here at RR you can go to the home page and click on the left side of the home page under Radio Features then click on "RR Database" then click on "MI" then click on the county you want, to get. http://www.radioreference.com/apps/db/?stid=26
There are pages of great lists there.
In addition to the db already listed, you should jump over to the Michigan forum (see what it says in the writeup in bold for this forum? hint hint). There's also a very active Yahoo group for Michigan here...you can never have too many sources of information in this game...