This is software I've written for myself which you may (or may not) find useful. Unless otherwise noted, everything here is released under the GNU General Public License (GPL). There is absolutely no warranty that any program listed here will behave in any fashion, and all programs are provided "as is."
Oh, this is pretty much Linux stuff, though some things will run under Unix-like systems, and the Google Calendar RSS parser should work on any web page.
Gnome 3 Random Wallpaper is a bash script to change your background. Given a directory and a time interval, it selects a random picture from the directory and puts it up as your Gnome wallpaper for a random time inside the time interval you specified. See the Blog post to comment on the software. You can run the command as
gnome3_random_wallpaper T1 T2 DIR
Where T1 and T2 are times in seconds, and you want the wallpaper to change at some time T where T1 < T < T2. DIR is the full path to a directory that contains pictures. If it contains some other files, that's OK, the script will skip over them. You and put the command in your startup applications.
setbg is a Perl script that randomly changes the wallpaper picture in the background (root) window of your X11 session. You specify a set of pictures to work with, and a time frame, i.e., change the picture every 60 to 120 minutes. setbg is known to work with the FVWM and ICEwm Window managers. I don't believe it will work with GNOME or KDE. It should work with TWM and its derivatives, but it's been a long time since I tried any of those.
Requires a package which will draw a picture onto the root
window. I use ImageMagick,
but other programs should work.
This program doesn't work GNOME. If you're lucky and still running GNOME 2, use the Gnome Background Switcher. If you're stuck with GNOME 3, use my Gnome 3 Random Wallpaper Script, above.