TechCrunch's post, "Foreclosures Shown On Scary, Encroaching Heat Maps," led me to Hotpads.com and to testdrive the site. It's very cool and has useful data on the U.S. housing market, and of course other information if you're looking to buy or rent.
So anything that's red or a shade of red it not good. My current home of Palo Alto is in a blue area and seems safe.
LA looks hot, in a bad way.
My hometown of Northbrook, IL and Chicago overall doesn't look too healthy either.
Other real estate sites to check out: Zillow and Trulia. We used both of these sites when we were house-hunting a couple years ago. I preferred Trulia's user-interface (UI), but Zillow seemed to have more useful information and tools.