Example:
http://sfbay.craigslist.org/search/apa?query=&srchType=A&useMap=1&minAsk=&maxAsk=&bedrooms=
Wait, when did this happen? This is very useful.
There is a website called PadMapper that used to pull data from Craigslist and display it on a map like this. They had been doing it for years. However, some time this year, PadMapper received a cease and desist notice from Craigslist. I suppose it makes sense that Craigslist was putting together its own mapping service.