Stamen teamed up with MySociety to produce some lovely travel-time maps of London. My favorite is the interactive travel + housing prices map:
Next, it is clearly no good to be told that a location is very convenient for your work if you can't afford to live there. So we have produced some interactive maps that allow users to set both the maximum time they're willing to commute, and the median house price they're willing or able to pay.
The commute time slider makes a lovely Mandelbrot-esque pattern as you pinch the times together. (via o'reilly radar)