Google Earth Pro - free
For those who haven't already signed up, Google Earth Pro, is now free for individuals. Until recently, this has only been available for $399.
I've already spent a few hours looking at places we've lived in, visited, or are just plain curious about. The interface takes a little practice at the close in scanning, but the definition is excellent, and the 3D effect is awesome.
All of the download sites have it, so be careful if you use them for the download, as unless you read the instructions, you may be signing on to some adware sites.