From Panda Systems:
PandoFrame is a freeware Macintosh application that allows you to place picture frames on your desktop. It's like Stickies for pictures. The picture frames set above any desktop pattern or picture you have, and can be arranged anywhere on the desktop. Frames can be any of nine shapes and come in a variety of colors and patterns. You can even create you own custom frames! They are perfect for displaying pictures of your loved ones, family, or even your pets!