I installed an Ubuntu version about 6 months ago, and in the appearance settings, I could check a box that made the windows "wavy" when you move them. Like, whenever you moved a window side to side, it made them look like gravity was affecting it. I forgot what the term was for this, but I can't seem to find a place to do this in the latest version of Ubuntu.
There are multiple ways to set wobbly windows up.
The traditional way to do this is by using the CompizConfig Settings Manager (ccsm). Install it by searching for it in the Ubuntu Software Center or by entering in a terminal:
sudo apt-get install compizconfig-settings-manager
You can then open it by searching for it in the Unity dash or by running ccsm in either the Alt+F2 prompt or a terminal.
Once in CompizConfig Settings Manager, look for the Wobbly Windows plugin under Effects:
All you should need to do is click the checkbox next to it to turn the plugin on, and windows should start jiggling around. You may have to restart compiz with a compiz --replace in the terminal or Alt+F2 if it doesn't take effect right away.
Within the plugin itself you should also be able to tweak some related settings to configure it just the way you want it.
WARNING
CompizConfig Settings Manager is known to break Unity if you mess
around with certain settings or options in it, even ones that seem
innocent enough. You are taking a risk by following these instructions
or any other answers that recommend the use of CCSM.
If you want to enable wobbly windows but don't want to take the risks involved with using ccsm, you can also set this option using Ubuntu Tweak, under Tweaks > Compiz Settings > Desktop Effects:
See How do I install Ubuntu-Tweak? for installation instructions.
