Firefox/Chrome: If you're tired of clicking through page after page of search results and would prefer to simply scroll through the pages on an infinite rotation, AutoPagerize enables endless scrolling.
Available as a Chrome and Firefox extension, as well as a Greasemonkey script for Firefox, AutoPagerize takes paginated query results and strings them together into a seamless document. It's not perfect—not all sites can be modified with the AJAX magic of AutoPagerize—but it works on well on popular sites like Google. Instead of clicking through page after page of search results, you can just keep scrolling—or paging down, tabbing, or however you navigate down the page.
AutoPagerize is free and available for Chrome and Firefox. Have a great extension or tweak for enhancing your web-browsing experience? Let's hear about it in the comments.