There are a number of sources that compile this information, but they all seem to have slightly different approaches. However, I think you can get a very good idea about what is happening in any local market right here on Trulia. See the web reference for Boulder below. As a visual learner, I especially like that Trulia graphs a lot of the information. Give it a look. You will have to scroll down a little to get to the graphs.
Prudential Real Estate of the Rockies
(Soon to be Berkshire Hathaway HomeServices)