One of the best features of opera makes it to Mozilla:

Mouse gestures in Mozilla. If you're running Mozilla -- my new bestest friend -- you should immediately install the Mozilla Gestures add-on. Gesture support works like this: hold the mouse down and zoom right to go forward, left to go back, up to open a link in a new tab and down to open it in a new window. Booyah!

Link Discuss

(Thanks, Dan!) [Boing Boing Blog]

I'm off to check it out now.