SearchBox Sync is an add-on for Mozilla Firefox. It automatically updates the search bar with your search text whenever you search from a web page directly. The most common search engines (Google, Yahoo!, Live Search, YouTube, ...) are automatically synchronized, and custom rules can easily be added for those that are not detected.

If you like this add-on, you will probably want to try SearchWP.

More information on Mozilla Add-ons

• Synchronize the search box content with any search engine or web site with a search form.
• Many default synchronization rules are included: Google, Yahoo, Microsoft Live & MSN, Amazon, eBay, Wikipedia, del.icio.us, Flickr, YouTube, MySpace, Facebook, Mozilla Add-ons, SourceForge.net.
• Custom synchronization rules can be added easily even if you don't know what's a regular expression.
• Included translations: Chinese (Taiwan), Dutch, English, French, German, Italian, Japanese, Polish, Portuguese, Russian, Slovak, Spanish