Mark Pilgrim developed a user script for Greasemonkey called Butler that attaches to Google pages (unfortunately only google.com - it doesn't work with google.de) and, for example, adds links that refer to other search engines, removes Google ads, and works a bit on the typography.
In principle, it's something like autolinking, but functionally goes far beyond that - with Greasemonkey you can fix shortcomings with small user scripts (in JavaScript, which must be activated for this purpose). And that's exactly what Mark does with the Google search results pages.
There is an entire repository with further user scripts for Greasemonkey. I particularly like the script for creating "persistent searches" in Google Mail. It integrates so well into Google Mail that you hardly notice it's not from Google at all.