Learn how to make an image that can repeat in all directions in Photoshop 7.0 or later. Tiling images are great for desktops.
Step 1: Get a Good Picture
The picture you use should make sense when tiled (for example, tiles). A good example of a bad tiling image is one of a street sign, since you only need one. I used a nice picture of Bacon. You can find a good picture on Google, or you can just use my bacon.