This is the one I'm aware of, I'm sure there are other groups.
http://www.reiaofoakland.com/home.html according to website their next meeting is 9/11/08
There is also one in Wayne, Livingston, and Macomb
What kind of investment properties are you looking for? I'd be more than happy to set up an automated search for you that gets sent via email. You can review at your leisure and just call when there's something you want to take a look at.