Make Firefox into a Powerful Command Line

I thought I’d share a computer trick I use dozens of times a day, which unlike most of my Mac-specific trick, is available for anyone who uses Mozilla’s Firefox Browser (or a derivative, like Camino).
The trick relies mostly on a combination of Firefox’s ability to make search shortcuts for the location bar, and google’s many nifty bits. With it your can utterly do away with the search bar in your browser and search from multiple search engines right from the location bar. But I’ve since expanded the trick to do much more, such as have an instant shorthand for any popular site, and get instant travel directions.