One great way to get your head around a large government dataset is to view it using Google Earth. I went on a hunt for the most interesting, striking and geography based government data sets currently available in the KML format used by Google Earth. There is a large gallery of tours and layers available from Google Earth's site, including some based on government data - but I wanted to look beyond them.

Here are eleven data sources (in no particular order) that have KML files ready and waiting for you to download. For some of these you will need to read the instructions associated with the KML to understand what you are looking at and what special features are enabled. Some have multiple datasets within a single KML file -- others include animations. Often when you open them in Google Earth they will start out with either a helpful note or a built in graphical key.

• USDA Forest Service: MODIS Active Fire Mapping Program: View fire detection data and incident information
• USGS Earthquake Hazards Program: real-time earthquake data (updated every 5 minutes!), geologic features and virtual tours of historic earthquakes.
• FEMA Flood Hazards: Stay Dry provides basic flood hazard map information from FEMA's National Flood Hazard Layer for specific addresses while NFHL (National Flood Hazard Layer) appears to be a more general application that displays flood hazard zones, floodways, base flood elevations, cross sections and coastal transects and much more.
• NASA: Goddard Scientific Visualization Studio: provides various visualization layers including Tectonic Plates Boundaries and African Fires during 2002. Dig through the various categories, there is a lot here.
• Nasa Jet Propulsion Laboratory OnEarth: multiple options are available for viewing daily updated views of earth from satellites. Very striking!
• gCensus: provides access to data from the 2000 US Census. The site lets you browse for various elements of data and generate a KML file you can then view via Google Earth.
• Air Quality Now: provides current and forcasted air quality conditions for locations across the USA. It is a product of a partnership of multiple US Government agencies.
• National Weather Service: has a full page of KML layers related to all aspects of weather - past, present and predicted.
• National Gallery of Art: Afghanistan Hidden Treasures from the National Museum: visit Aï Khanum, Tillya Tepe, and Begram—that and examine Afghan Treasures
• National Park Service: National Register of Historic Places: provides Google Earth layers per region of the USA that mark historic places.
• District of Columbia Data Catalog: provides a wide range of data about our nations capital. You must supply some simple data to identify yourself before downloading these KML files. This is just a taste of what various regional governments are providing. Give your home state, district or territory's website a look to see if you can find KML data available.

Have a favorite KML formatted government data set I missed? Please share it in the comments. I found many of these by starting in Goggle's US Government Search and searching for Google Earth.