Timed Random Desktop Pictures are Here

[jove]

What you need

CronniX
Desktop Randomizer

both are available at Versiontracker

Read the CronniX help to understand the timing syntax (i.e */5 means every five minutes). Desktop Randomizer should be ran once manually to set up the preferences.

Apple: please make the set as desktop function a service.
Jessica Koch: please put timing into Desktop Randomizer.

[Red Phoenix]

Another good option is SwitchPic, which automatically changes the desktop without logging out and back in. It's nice, except it seems to have a bit of trouble when you want it to randomly pick more than 100 pictures. Anyway, you can get it at www.versiontracker.com

[Obormot]

Here's my problem with DesktopRandomizer... it's slow.

I want a different desktop pic with each login. With RandomBackground, I see my new background as soon as the loginwindow goes away; with DesktopRandomizer I have to wait ~10 seconds for the new background, during which time I see the previous picture.

Then again, RandomBackground doesn't follow aliases like DesktopRandomizer does, and for some reason it also gives me a new desktop with every Finder relaunch... weird.