I was stumbling through the Ubuntu customization websites yesterday and found this awesome wallpaper which changes with the time of the day.
The wallpaper pack can be downloaded from this location ^[1]. It is from Gnome-Look and is totally safe to use.

Using the wallpaper is as simple as it can get.

1. Unzip the file named AllDayLong.tar.gz to a convenient location on your hard drive.
2. Navigate to the folder created as “AllDayLong” or a custom folder, in case you created one.
3. Open a terminal window in that location. If the option is not available, navigate to the location from your terminal.
4. Execute the command

   sudo sh install

   This will generate an XML file in your folder( the present working directory in the terminal) and will generate the output as shown.
   

5. Now, go to your desktop, right click on an empty space and select Change Desktop Background.
6. In the window that opens, select add and from the file selection dialogue, select the XML file we just generated.
   

From now on, your wallpaper is animated with the color and the wallpaper changing with the time of the day.

If you liked this customization, you might want to check our previous tweaks and software compilations at this post ^[2].