Make any pages' search functionality available in the Search Bar (or "search box")...
AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.
Expands the context menu's 'Search for' item into a list of installed search engines, allowing you to choose the engine you want to use for each search.
Easily navigate through Google search results using a fast, simple and useful Tag-Cloud technique. Use our Topic-Mapping-Technologies for quick access to answers, news, videos, blogs, Wikipedia and more. Install now and boost your search.
Autosizes the searchbar as you type, cleans the query or reverts to your default search engine after submitting. Supports almost all themes and various search bar related extensions. Useful for saving space on a small screen.
LinkExtend provides meta-site-ratings for computer safety, child safety, company ethics, and popularity. Safety results come from eight online services giving you a safer browsing experience. Site links, titles, files and reviews are also included.
The Related How-To Videos Sidebar shows you a list of free how-to videos related to the web pages you browse.
For extra wonderment, try using it along-side the StumbleUpon toolbar!
GoogleTube is a nifty little player for YouTube, accessible from the status bar and within Google, Yahoo! and Bing search results.
Think of it as a combination of a search and recommendation engine for music, live shows, movies trailers and more...