Nike's Map It
It's been a while since Google Maps Mania has had a look at Nike's 'Map It' site (over three years in fact). It wasn't surprising then to find that Map It has made quite a number of improvements in that time.
Map It uses Google Maps to allow runners to map, describe and share routes that they run. The site now has a nice heat map interface that helps you tell at a glance where you can find a concentration of mapped runs.
When you zoom in the map markers actually display the length in kilometres of each run. If you hover over the map marker the route is shown instantly. Browsing through the mapped routes to find the one you want is therefore very easy.