This has got to be the most awesome Google Maps hack ever. Finally, I know that when I bike to school, I'm going around 1.4 miles. To a friend's house that I often bike to, it's about 2.12 miles; another's is 2.7 the way I currently go, which could be cut down to about 2.3 if I take a slightly different path (I knew there had to be a shorter route, I just didn't want to get lost figuring out exactly which way it was). The park is 1.7 miles. My large running loop is 3.25 miles long; the shorter one that I occasionally take is 1.3 miles long. And the middle one is 2.3.
Woot. Now I'll finally have running mileages in my journal as well as times, without having to bust out the car's trip counter (which was too much of a pain to ever do). I am happy!