The OpenSearchFox extension allows you to quickly and easily create a search plugin from any web site. Now after you first install this extension, you might be a little lost with what to do. All you need to do is right click on any search form (like the one found on FirefoxFacts.com for an example) and then you will have a new menu item to select to create your search. You can also change the icon for the search plugin too – just in case the favicon for the site isn’t “doing it for you” or it does not have one.

Update: Check out this screencast to get a tutorial on how to get up and running with this extention! (Thanks Eddie!)