Tip: Use Safari to set your desktop image
Next time you see a really nice image on the Web, make it your desktop image!
- Right-click on the image in Safari.
- Choose Use Image as Desktop Picture.

Safari copies the image to /Users/YourUserName/Library/Safari/Safari Desktop Picture.jpg and only maintains one image at a time. And be sure that the dimensions of the picture match your computer monitor to prevent awkward resizing.
Handy!