Are you a big fan of Google’s custom search feature, which allows you to customize your own search engine to fit your needs?  The Custom Google Search add-on for Firefox, in that case, is a perfect companion. 

In a nutshell, this extension for Firefox allows you to create, use and mange your own Google Custom Engines from within the Firefox browser interface. 

You can pick up the Custom Google Search add-on for Firefox on the Firefox Add-ons web site.