Google Mapplets are mini-applications that you can embed within the Google Maps site. Examples include real estate search, current weather conditions, and distance measurement. Mapplets are Google Gadgets [1] that can manipulate the map using Javascript calls that are derived from the Google Maps API [2].
http://www.google.com/apis/maps/documentation/mapplets/index.html [3]
Links:
[1] http://www.google.com/apis/gadgets/
[2] http://www.google.com/apis/maps/index.html
[3] http://www.google.com/apis/maps/documentation/mapplets/index.html