http://www.mapmyrun.com/
This website uses Google maps (with most of the same features). You can zoom in on a location, outline a course, and it calculates the distance and the elevation changes throughout the course (so you can see if there are big hills, for example). You can also see what your pace per mile is, calories burned over the course, and miles per hour at that pace. You can save the courses that you outline for later reference as well.