If you’re using gnome desktop environment in your ubuntu,there’s an interesting thing that you can make your desktop wallpaper alive by setting a screensaver as the desktop wallpaper.
Open a terminal emulator and type the command:

gconftool-2 --type bool --set /apps/nautilus/preferences/show_desktop false

It sets the /apps/nautilus/preferences/show_desktop setting to false,and nautilus is no longer drawing the desktop.
Now,launch a screensaver as desktop wallpaper by this command:

/usr/lib/xscreensaver/screensaver_name_here -root

Following command lists a number of screensavers provided by the xscreensaver-data package,and you can choose one and use above command:

ls /usr/lib/xscreensaver

If you want this functionality when login,go toSystem->Preferences->Startup applications.
Click on Add,and type this command in command area.

/usr/lib/xscreensaver/screensaver_name_here -root

If you want to turn this functionality back,uncheck this application in Startup applications,and run this command:

gconftool-2 --type bool --set /apps/nautilus/preferences/show_desktop true && nautilus

Log out and back in.