Bonneville Crater: Image credit: http://www.jpl.nasa.gov/mer2004/rover-images/mar-15-2004/captions/image-1.html.
NASA's Spirit rover has taken a beautiful panoramic image of the Bonneville crater. Here's a 1024x768 wallpaper of the crater. The original image was quite wide, covering 180-degrees, so it doesn't quite fit a computer screen normally - this image has been cropped a bit. Spirit recorded this photo on March 12, 2004, using its panoramic camera. By taking such a detailed image, scientists can get a good idea about the surface material at the crater.