MapServer, originally developed at the University of Minnesota, “is an Open Source platform for publishing spatial data and interactive mapping applications to the web.” MapServer is a powerful tool for sharing geographic data and its uses are found all over the web.
The data comes from the Iowa Environment Mesonet, and the current map example displays historical CONUS NEXRAD base reflectivity. Their site has a number of other weather related datasets that are updated at regular time intervals. With this in mind, and using some of my other examples, one could combine a number of these data sources and create a pretty interesting weather related Google map mash-up.
Several of their datasets are also time enabled, meaning that one could create time sliders using this data. When using this code, note that several different settings are used to make the NoData values transparent, and to tack the map data to the Google Map. In this example, the user cannot turn the MapServer layer on or off.