I like the suggestion by Teko for a "current site search" option for Google, but understand what you say about it deviating from what the add-on does. But what about this approach, which generalises the idea and might fit in a bit more naturally. Currently, the web address has %s replaced by the text selection. What if also %d (say) was replaced by the current domain name. The user could then manually edit the web addresses exactly as they like, for any search engines of their choice. For example, for a Google site search they'd change "%s" to "site:%d %s". This concept could be extended to %u (say) being replaced by the URL. It could then be used to send the whole page to Google Translate, HTML validation services etc. (In this case, the add-on would also need to work with the Context Menu you get when there's no text selection). I realise that it's a bit more work for the user to set up initially, and that there might be technical reasons why it's not suitable - but I thought I'd put the idea forwards.