Scribble Maps is an interesting mash-up that turns Google Maps into an online whiteboard.
It adds common drawing and painting tools such as pencils, lines and colored brushes to the Google Maps interfaces so you can easily sketch freehand drawings, insert text, or even add custom shapes anywhere on the map.
Scribble Maps may look like a fun app but there are some useful applications. For instance, you can create detailed driving directions to your home by adding annotations to a Google Map. Or if you are going hitchhiking, you can plot the exact trail on Google Maps and share that map will fellow hitchhikers.
If you are looking for something similar in Google Earth, try Earth Paint - it’s a free plugin that adds painting and drawing capabilities in Google Earth.
The tool adds a variety of drawing tools such as a freehand pencil, ellipse, rectangle, polygon, and text tool. When a drawing is complete, you can publish it as a transparent overlay to Google Earth.