A new (and important) Google Api, that makes remixing the web a lot easier and some really nice 3rd-party Google Earth extensions (mainly for infovis):

Googe Feed API:

• Google AJAX Feed API – Developer Guide
  With the AJAX Feed API, you can download any public Atom or RSS feed using only JavaScript, so you can easily mash up feeds with your content and other APIs like the Google Maps API.
  (tags: api ajax javascript google json)

Google Earth Add-Ons

• Google Earth Community: World Designer
  (tags: google googlearth software overlays kml)
• GE-Graph for Google Earth
  GE-Graph was developed to generate graphs from kml files saved by Google Earth.
  The data can also be typed into the application or pasted from other applications.
  The file generated by GE-Graph can be exported to Google Earth.
  (tags: software freeware google googleearth visualization graphs)