On Mars, Opportunity is literally spinning its wheels, carefully extricating itself from the deep sand dune it’s been stuck in for the last few weeks. The rover was going backwards at the time — they alternate forward and reverse driving due to wheel well lubrication issues — so now the rover is actually moving “forward” out of the dune.
I took images from Opportunity’s front and rear hazcams in the raw image gallery and animated them, for an idea of the rover’s progress: front view, rear view (1MB animated GIFs). Note that these are over the span of several days, which is why the shadows keep changing.
JPL also has a closeup video of Opportunity’s left front wheel spinning in the soil.