Jog.fm is a site where you can get music to listen to while you are exercising. So far, three different activities are supported: running, walking and cycling. In all three cases, music is found simply by specifying your actual kilometer time for Jog.fm to come up with a suitable playlist.
Alternatively, you can browse through these playlists that other people have favorited and download the ones which are more popular directly.
And in addition to providing you with music to enliven your trots up and down the city, the site features a route planning application. This will let you add points one by one until you have devised a route that will test your endurance to the limit. Or (if you are a bit like me) one that will take you through all the trendiest spots in town. As long as you are exercising as intended, I suppose that it makes no difference, right?