If you hadn't noticed, Goggle Maps now has Real Estate Listings. To see what listings they have in the area your interested, go to http://maps.google.com and double click the map repeatedly to zoom in to the area your interested in. Next, click on the button titled "more". There should be a check box there that says "Real Estate" that you can check.
And here's a live link to this
Southern Michigan Google Real Estate Map
Here's how it looks as an iframe on your site:
View Larger Map