Very handy and underrecognized! Rated 5 out of 5 stars
This has to be among the most under-recognized add-ons out there. Fantastic time- and click-saver, so much so that after some easy set-up you'll likely search a lot more -- with the CONTROL you want as well.
For example, here's one of my several entries, which automatically searches (with the right-click context menu) for any highlighted text in Avax:
You can perform actions besides search as well. This sends any selected URL to Google Translate with "detect language" to English:
I used to do the same thing in IE with IE7Pro. Very happy this add-on provides the capability to FF.