A black skin for google web and/or image search. This skin looks best with a dark Firefox theme.
There are options for when to apply the skin for each page including always, never, adding a status bar button or a timer (the normal white can make it easier to read when its sunny).
It also has an option to bypass Google Images "page/image info" dual screen when you click on a result. It sets the image to link to the actual image and the green link underneath to link to the page.