Someone has put up a nifty free Google Maps mashup called KML Writer which let’s you draw a path or a polygon which can then be written into a KML file (GE file). Simply move the map to a location where you want a path or a polygon and start drawing. Then type a name and description and select “Add to KML”. When you are done adding KML, select “Open KML”. The file should then open in Google Earth.
For an example, I created a space elevator 
(an idea proposed by Arthur Clarke in his science fiction book “The Fountains of Paradise”).
The tool works pretty well, but is not as convenient to use as Google Earth Plus (US$20/year) which allows you to create and edit paths and polygons within Google Earth. GE+ lets you edit the colors and text, change the extrusion of the polygon, and with GE+ you get faster access to the GE database. I recommend GE+ to serious GE users, or those needing these types of features on a regular basis. But, if you just need to do something quick this free KML Writer is an alternative. KML Writer was written by Simple Spatial Solutions. Via OgleEarth.
About Frank Taylor
Frank Taylor started the Google Earth Blog in July, 2005 shortly after Google Earth was first released. He has worked with 3D computer graphics and VR for many years and was very impressed with this exciting product. Frank completed a 5.5 year circumnavigation of the earth by sailboat in June 2015 which you can read about at Tahina Expedition, and is a licensed pilot, backpacker, diver, and photographer.
This tool is not handy…
I use another free tool to draw paths : KML Path Generator.
It’s simple :
1) create a folder in GE
2) fill it with placemarks and order them the way you want the path to be created
3) save the folder in KML format (not KMZ !)
4) go to http://dev.bt23.org/keyhole/pathgen/ and give you KML emplacement
5) Click on “Upload KML folder”
6) dowload the result in KML format 😉
7) that’s all 😉
Simple and handy. But there is no ploygon capabilities…
I think this tool is very handy. The KML Path generator requires placemarks which can’t be made with one click. When I want to save a mountainbiketour I just click the path into the browser and then save it. Making a placemark for each waypoint would take ages. Therefore I love this tool, thanks for telling me about it! 🙂