Addon of the day: Greasemonkey

This addition to your Firefox repertoire was such an easy target for our AotD feature that we deliberately waited to draw the guns on this one. Greasemonkey is single-handedly the most powerful addon that an installation of Firefox will ever contain. Leveraging the power of thousands of installable scripts, the possibilities are as endless as cleaning up Gmail, enabling YouTube downloads, or adding Wikipedia searches to any highlighted word.