If you haven't already checked out google earth, it's awesome. If any of the trails you run or plan on running are captured with the high res mode, it's a very helpful tool for determining the terrain of a given trail. This program overlaps topo maps with high res satellite images (enough to resolve cars and bushes) to give a detailed 3D view of the terrain. You can rotate maps, change your elevation, and move around in a very fluid manner. It only works on PCs right now, but they have a mac version in the works.
http://earth.google.com
Linear Mode
