Wonderful Rated 5 out of 5 stars
This thing does so much you could spend many hours tailoring every option to your needs. My needs happen to be modest: I normally use only Search, Translate, and Convert. LI allows me to see only those three functions in the popup menu, giving it a nice streamlined, minimalistic look.
Search is especially appreciated. A swipe of the mouse, two quick mouse clicks, and the results from my search engine of choice are right there.
Conversions of distance, currency, etc., are normally pretty laborious since they involve a trip to one or more specialized websites, but LI's drill-down Convert menu gives you anything you need in a few seconds.
In a nutshell: when a new version of Firefox disables 75% of my add-ons due to incompatibility, this is the one that hurts the most to lose.