This from O'Reillyi Radar.  (Yes, whoever wrote the hed surely meant "travel-time maps".) 

Dynamic Time-Travel Maps From MySociety and Stamen

UK-based non-profit MySociety teamed up with Stamen Design to develop some innovative time-travel maps. The snapshot of the map that you see above shows where you can live in London with a commute between 30 to 60 minutes where the median house price is over £230, 000. As you adjust the sliders, the map changes in realtime letting you adjust the commute times from 0 up to 90 minutes and the housing price from 0 to £990,00. The Department of ...   more »