I'm going post crazy tonight.
Here are some sites that use Google Maps in ways I find interesting.
This site allows you to tag, with rectangles, any area of the earth at a wide range of scales. The image above shows the San Diego Velodrome which I tagged myself. This is a great time waster even if you're only exploring.
This site shows the path of all the total solar eclipses for the next thirty years. Clicking on the map brings up statistics for that spot on the earth. Start planning for the next one in the USA, in 2017!
Ever wonder how to make an earth sandwich? First, put a piece of bread down where you are, and then quickly (before it gets eaten by your house mice), using this tool, put a piece of bread exactly 1/2 the way around the world. This tool tells me that my second piece of bread would get very soggy in the Indian Ocean.