3D Printable Track Design
A visitor to the site -- t00tie -- sent over a link to a very cool 3D printer model for plastic tracks.
The model is called "Moon Rover" created by emmett on the site Thingiverse. The track design is derived originally from a expanding bracelet and it utilizes the pliability of ABS with the natural flex of the deep inset hinges between each cleat to get a simple yet effective tread. Apparently, the cogs at each end nicely mesh with the hinges and provide positive traction.
I like that this photo shows the extruded strands of ABS stacked to make up the track width. It looks to me like the design would also allow for some springy suspension properties, too. However, power capacity in a larger scaled up version may be an issue as the tread will stretch and deform under stress.