Don’t you love how swiss knives seem to have a tool for every occasion? Well the WebSwissKnifeToolBar is a Greasemonkey script that does the same for your browser.
Brought to my attention by its creator, this user script adds a lot of functionality to Firefox. Here are just a few things it can do.

Easy an fast search for: Google, YouTube videos, and Wikipedia (Spanish and English)
Translator EnglishSpanish, with just a click
Spanish dictionary (RAE), with just a click
Convert [...]