Three great mapping websites to check out:
- Wayfaring: allows you to easily build your own maps. I am using it to build a map of every place I have ever lived.
- Neighboroo: provides different types of overlays for Google Maps, such as population by race, population density, crime rates, average income, etc.
- Frappr: another site for making your own websites. This one allows you to add them to MySpace and has other social features
- Wikimapia: their goal is to describe the whole world using a wiki and Google Maps
Enjoy those sites. If you want more, visit Google Maps Mania. This site has a comprehensive roundup of all Google Maps mashups.