Update(Sep 21, 2008) : As of now Nextplease! plugin doesn't work with Firefox 3
Here is plugin that I can't do without.NextPlease! is a highly configurable extension that allows you to jump to next and previous links on search results pages, like Google, Yahoo, Ebay, Amazon, and many other sites. NextPlease! can be triggered via keyboard shortcuts, toolbar...
The older version of this plugin used to work fine with the Next/Previous links were image links but simple simple hypertext links were an issue. In the screenshot of the NextPlease! menu you can see it that only image links can assigned. The newer versions of plugin allows the use of simple link phrases too.
The plugin comes along with a comprehensive documentation too. Usually firefox plugins don't have great documentation, but this one does!!!. Overall this plugin is neat and makes surfs a hundred of more page listings easy.