Adds extremely useful functionality to browser navigation. I second the other review stating it would be ideal to be able to set the shortcut. Although it's sort of a bonus feature to able to override a Firefox shortcut with ctrl-d, overidding the standard redo shortcut ctrl-y is a hindrance.

What I would also like is an option to not highlight the text by default, instead placing the cursor at the end or beginning (I'm most often appending/modifying search queries).