From the wiki:
The Data-gov Wiki is a project being pursued in the Tetherless World Constellation at Rensselaer Polytechnic Institute. We are investigating open government datasets using semantic web technologies. Currently, we are translating such datasets into RDF, getting them linked to the linked data cloud, and developing interesting applications and demos on linked government data. Most of the datasets shown on this page come from the US government’s data.gov Web site, although some are from other countries or non-government sources.
Try out their Drupal site with new demos:
My misgivings about the “openness” that releasing government data brings to one side, the Drupal site is a job well done and merits your attention.