There's also a few more that a lot of posters seem to like. Each has slightly different features, so enjoy browsing through them (and the others mentioned by the posters above) to see if you can find something that suits your needs:
MSN Wallpaper Manager - (Download MSN Wallpaper Manager
) - MSN Wallpaper Manager from the Windows Live team lets you change your desktop wallpaper at regular interval or based on time (like at lunch, working hours, weekends, etc). MSN Wallpaper Manager automatically downloads wallpaper library in Background to provide refreshing wallpapers every day. You can also personalize by adding text, speech bubbles, graphics, + element 7 foreground images.
(The link above was thanks to swarfega
Automatic Wallpaper Changer (download: www.awc.smurphy.co.uk
) and Any Wallpaper (download: www.anyutils.com/anywall.php
) continuously change the desktop picture after a certain amount of time. Look at the page about automatically changing the desktop picture
for more information about these tools.
Desktop Wallpaper Changer Gadget - Desktop Wallpaper Gadget Download - Softpedia