I love browser add-ons. And Firefox is loaded with them, even though some don't work properly or just aren't that useful. But Hyperwords is worth its weight in gold. It's simple to use: just highlight and righ-click any word on a Web page and you will be presented with many options including, a wikipedia lookup, dictionary or thesaurus lookup, search images and video or perform a Google search. Look up a word in another language, convert currency and temperatures and even choose blocks of text to tag, blog or email to others. The number of options available is stunning. This extension is truly a time saver, bringing several important tools of the Web right to your mouse.

Watch a short demo of Hyperwords.