Quick Google is a useful Chrome extension. You can search Google without leaving the current page and see a preview of each result.

Google Homepage Reloaded is a greasemonkey script, which gives users the ability to click Google logo on Google homepage to change the website they search.

List of advanced search operators in Google Wave.

Xmarks SearchTabs improves the Google result page by adding tabs containing the top web sites related to your search.

Revert recent changes on Google’s homepage and remove S-U-P-E-R-sized search box and other elements with this greasemonkey script.

The Real Live Search is a live search engine created using Bing.com API. It shows search results as you type your query.

fefoo is the simplest tool to search many search engines at same time.

Blinkx is a wonderful search engine for videos.

Twicsy is a search engine for images shared on twitter.

BlindSearch compares results from Google, Yahoo! Search and Bing.

At the very first sight, Topsy would seem to you as another twitter search tool but it is a much more advanced search engine for conversations.

URL bar search is another handy Firefox add-on which makes searching easy with multiple search engines.

As the name suggests Twoogle = Twitter Search + Google Search.

KwiClick is an essential Firefox add-on for everyone who searches the web! You can search the internet right from your status bar, without leaving the current page.