One of my many Lego NXT project ideas is to build a Rocker-Bogie system similar to the Mars Sojourner, Spirit and Opportunity rovers. It turns out a similar mechanism is ipresented by Brian Bagnall in his book titled Maximum Lego NXT: Building Robots with Java Brains.
While I wait on that book to move from my Amazon wish list, to my shipping list, I found a few interesting videos:
And a site by Kevin Knuth where the rocker bogie suspension has already been built. Kevin’s site has a few more video examples.