On that page, there's a notice for the Low Income Family Waiting List with a May deadline that you should look at:
If you qualify for Section 8, here's that page:
And it looks like thier search engine for low income rentals is here:
You could also try StartRenting.com, which is a more general rental search engine specializing in the Madison, Milwaukee, Fox Valley areas: http://www.startrenting.com/search.php?mkt=mke
Hope this helps, good luck!