There are real estate sites like Zillow, eppraisal and Trulia giving away information like the following via APIs:

• Mortgage rates (for all the states and national average)
• Various statistical info like history of home prices for zip codes, neighborhoods and states.

If you do not want to use the widgets provided by these sites and would like to create cool, custom charts you may want to consider using Fusion Charts.

Here is the mortgage rates comparison chart (obtained using Zillow API) shown using Fusion charts.

Mortgage Rate comparison Chart (US Vs CA)

View Code snippet for the above.

View more examples using Trulia API.

Check out their web site for free download of the software and for many good examples to get started with. If you want to use this on production sites or you do not like the ‘evaluation label’, you may want to purchase a license.

Note: FusionCharts helps you create animated & interactive charts for web applications. It can be used on PCs, iPads, iPhones and a majority of other mobile devices.

FusionCharts leverages Flash and JavaScript (HTML5) to create stunning charts, and works with both XML and JSON data. It can be integrated with any server-side technology (ASP, PHP, JSP, ColdFusion, Pearl, Ruby on Rails etc.) and database.