If you're looking to build a mashup, you're going to need data. Sometimes this will be your own, other times you'll bring together data from one source and a visualization (such as Virtual Earth) from another.

For people that are looking to try doing mashups with data, one of the recommendations I have is to check out the SuperDataPack from StrikeIron. This is a set of data services that you can get access to for no charge (up to 10,000 hits/month), and there's some great data to use for your mashups.

Today, I posted a new sample in the resources section called 'Personal Government'. This takes a single piece of information - a 5 digit zip code  and then interacts with 5 different services to retrieve information provided by multiple different sources within a common area, government. The sources range from the federal government (senators), state government, county government, and city government. In addition, it also retrieves census data for zipcode as well.

Both a PDF of the lab, as well as a completed solution have been posted.