Firefox w/ Greasemonkey: If you search Google Images with the intent to jump right to the full-size image and not to check out the site itself, this script will save you an extra click every time.
It might seem like a small thing to tweak, but if you frequently hit up Google Images and hate the current flow of Find Image -> Click Image -> See Full Size Image and would prefer it to be Find Image -> See Full Size Image then Google Image Relinker will hack the middle step out of your image search workflow. Want to see the actual site? Just toggle Greasemonkey off and take a peek.
Google Image Relinker is a free Greasemonkey script and requires Firefox with Greasemonkey installed. Have a tip, trick or user script to speed up your workflow? Let's hear about it in the comments.