I'm sure this is a repost, but I never saw it on here...
www.googleearth.com
A downloadable program (about 11 Mb) that allows you to zoom in on anywhere on the world. This is a huge improvement over the older sattelite photos you could get from google. You can zoom in much further, tilt, pan, spin, zoom, etc.
This program is far more interesting and entertaining than I would have ever imagined from a free program.