WallMagician is a free desktop wallpaper manager for Windows.

Features found in WallMagician:

•Uses image filtering to preserve image quality when stretching/resizing images on your desktop. The following filtering methods can be selected: Lanczos (default), Mitchell, Nearest, Spline.
•Supports drag/drop operations from Windows Explorer onto WallMagician's list box (can drag folders or images)
•Categorize your wallpapers into Wallpaper "lists". Each list can have virtually unlimited number of wallpapers
•Wallpaper styles supported: Tile, Center, Fit to Screen, Custom Position with Tile Around Image option (not available in Windows 95/98/Me), and Auto Fit
•Each wallpaper can be customized to use a specific wallpaper style
•Ability to rename image files on disk or send unwanted image files to Recycle Bin
•Ability to clear your current desktop wallpaper, hide desktop icons, and change desktop color
•Thumbnail tab displays thumbnails of all your wallpapers in your current list

Plus many more.