I posted a little script here to compare real estate by zipcode via Zillow:
(Don't push "enter" - just type a number and wait. I'll fix that eventually.)
It's using the Zillow API, which is sort of neat and useful, but I wish I could get raw data as well as rendered charts.
Real estate is local, after all. Here's a comparison of Beverly Hills (where prices have actually risen since the onset of the credit crunch in 2007) vs. Stockton (where there are a whole lot of foreclosures).