BackFlip - description from Softdepia.com:
Cycle your wallpaper. It doesn't matter if you are a power user or a newbie, if you have a computer you want make your working space look nice. Windows let's you put a wallpaper at desktop. And BackFlip let's you change wallpaper automatically. It is boring to look at one and the same wallpaper al the time. With BackFlip you can cycle as many wallpaper images as you can find.
...with mouse click in tray
How many actions do you normally perform to change wallpaper? Five? Seven? BackFlip will change wallpaper instantly - just one click on icon in tray.
...once a second or once a year
BackFlip can cycle wallpaper at any interval from once a second to once a year. It has four cozy sliders - seconds, minutes, hours and days. You can set time moving this sliders with mouse.
...from hard drive
BackFlip allows to add to wallpaper list single images as well as whole folders. You can preview images as thumbnails before adding them. You can also change the order of images and folders in the list.
...from local network
If you are not satisfied with number of images you have at you hard drive just want some new fresh wallpaper, you can add images and folders from the local network. Now you can make a wallpaper from any image in any available network resource.
If you have explored all images in the local network and want more you can always find some sites in Internet offering wallpapers. You can add link to some wallpaper site to BackFlip and it will take image automatically. Downloaded images can be optionally cached on your hard drive in order to be loaded faster the next time.
...in 26 formats
BackFlip supports 26 formats. It doesn't matter in what format is image - common .gif or .jpeg, Adobe Photoshop .psd, some vector format like .emf or .wmf - BackFlip will make a wallpaper of them all.
...with 6 effects
Ability to apply effect to image before making it a wallpaper is a unique BackFlip feature. AutoContract automatically fixes image contrast. Grayscale converts image to grayscale palette. Negative makes a kind of photo negative of an image. Blur and Sharpen changes image sharpness - making it less and more sharp correspondingly.
...in 4 display modes
Four display modes are supported by BackFlip - center, tile, stretch proportionally and stretch to fit desktop.
...with advanced tile support
BackFlip gives you full controll over tile management. Four tile options are available: no zoom (image is displayed as is and number of tiles depends on image size and screen resolution), zoom proportionally with fixed number of horizontal tiles (you set number of horizontal tiles, number of vertical tiles depends on image, image is zoomed proportionally), zoom proportionally with fixed number of vertical tiles (you set number of vertical tiles, number of horizontal tiles depends on image, image is zoomed proportionally), zoom with fixed number of horizontal and vertical tiles (you set number of both horizontal and vertical tiles, image is zoomed without regard to proportions).
BackFlip is a "Free to try" program. You can download and try it for an evaluation period.