If you  have a graphics card and installed graphic driver,you can install compiz and enable 3D desktop on your ubuntu by the following steps.With compiz installed,there are several things that you can make your desktop lively such as different wallpaper on each workspace,put fishbowl on desktop,put real-transparent terminal on to desktop,and enable snow in ubuntu desktop

Install Compiz fusion

Just type this command in a terminal window:

sudo apt-get install compiz*

Enable 3D desktop

Right click on your desktop and select Change Desktop Background.

go to Visual Effects tab and tick Extra on.

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Now,go to System–>Preferences–>CompizConfig Settings Manager

in this window tick Desktop Cube,Rotate Cube and Cube Reflection and Deformation(Type in Filter area to find out them).

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then click on Desktop Cube to go to its configuration page,turn to Transparent Cube tab,do like following.

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Click General Options, turn to Desktop size tab and change Horizontal Virtual Size to 4 :

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Done.Press Ctrl+Alt and drag left mouse key,you will see:

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Tips:

You can also make your compiz run smoothly with this setting in compiz setting manager
More 3D effect see:Some more 3D effects in Ubuntu with Compiz