You might be aware of Google’s site: operator that lets you restrict the search results to a specific website. Search Site is a Firefox add-on based on Google Search’s site: operator, that lets you search the opened website for selected text on a webpage.

Select some text on a webpage and right click on it and select “Search Site For Selection”.

It also adds a button next to Search button in Firefox’s search box so that you can type a query into Firefox search box and click on the Search site button to restrict searches to currently opened website.

One thing i wished it should have supported is opening search results in a new tab while searching using selected text.

It is an experimental add-on and to install it, you’ll need to tick the check box asking you to install experimental add-on. [via gHacks]