Open travel-time maps of the UK
The MySociety project has produced an incredible set of travel-time maps of the UK, showing the voyage-time using color shading (red for close, blue for far) and contour lines to indicate each hour's travel -- they compare the overall travel time for going from A to B by rail and car and cab. They're laying an open geodata-bank for use in correlating house prices to travel times, cost-to-time, and generating realtime web-services. Link (via Oblomovka)
http://www.mysociety.org/2006/travel-time-maps/