Mymaps takes a copy of google maps and makes an overlay. Sort of what they used to call a mashup but without the difficult coding. Uses could be to map earthquakes, pollution etc. Any statisitcal dataset that has a geospatial component can be added as a google spreadsheet. The resulting location pins can then be colour coded to allow easy visualisation of the data.

http://www.summitstuff.com/mapping-magic/mapping-with-google-tools