Ann Arbor has a fairly large Jewish community, especially by proportion. Here are a list of synagogues in Ann Arbor;
(Someone who know's how to work this gizmo should also add the Chabad House and Hillel, both of which, if I'm not mistaken, offer services for Orthodox Jews. Although if you're Orthodox you probably already know this, and if you aren't you probably aren't considering joining up, but still....).
Plus Hillel has a Humanistic Havurah and a whole range of other activities for Jews of all sorts.
(Here's a page that lists those places and more: http://www.ssw.umich.edu/programs/ce/drachler/life_annarbor.html)