Just a little tip for Mac users out there.
If you are running OSX 10.4.8, there is a built in zoom feature enabled by default.
You can hold down the control button and scroll with your scroll wheel. If you have a Macbook or Macbook Pro, then you can hold control and scroll by putting 2 fingers on your trackpad and slide up to zoom in, and slide down to zoom out.
You can also invert the colors your screen by holding down Control-Option-Command and press 8.
Both of these features increased my productivity alot, mainly because of how it is seemlessly intergrated with the operating system. No extra software to install!