I've been playing around with the Google Maps Engine Lite. Here I uploaded the location of IASL (Iowa Association of School Librarians) members (Correction here: the file provided to me was actually IASL conference attendees. This is still interesting, but I will have to work on membership spreadsheet and create another map to compare the distribution) I was wondering about the geographic distribution. In order to make this work, I had to spend quite a bit of time correcting the data on the original spreadsheet so that it could be uploaded.
This is what it looks like on GoogleEarth.
I can see some interesting uses of this in the classroom.