Among the molecular motors of the cell, there are quite a few that appear to walk on two legs like we do. However, the rules in the nanoworld are very different from our world. Walkers there can't rely on gravity to keep them connected with the track, and they have to muddle through the chaos that is Brownian motion.
Researchers have been able to build synthetic walkers from DNA for a few years now, and recently have also introduced the first small molecule walker that matches the key criteria of the walking molecules in the cell.
I wrote a feature about all this which is out in Chemistry & Industry this week:
Walking in the nanoworld
Chemistry & Industry issue 19, pp 20-22
free access to full text (html)
A couple of macroscale walkers appear on the cover of the issue by coincidence.