In maverick, and I belive many old ubuntus, one could zoom in and out by holding super and scrolling with the mouse, but that doesn't work in Natty. How do you activate that again?
First of all you need to install CompizConfig Settings Manager from the Software Centre. Once you've done that then launch it, and find the Enhanced Zoom Desktop plugin.
Here you need to enable the Zoom In and Zoom Out mouse shortcuts. To get the same behaviour as in 10.10 then set Zoom In to Button4 and Zoom Out to Button5.
Works in 11.10 also. http://jdnash.com/2012/02/practical-ubuntu-part-2-of-2/