The basic idea here is that you can set up "Quick Searches" to simplify common tasks. Gina's article lays it all out very well, but I will summarize. Let's use Amazon.com as an example. If you go to Amazon's web site and right-click (cmd+click) in the search box and select "add a keyword for this search," you will get the dialog to create an Amazon quick search. You can name it Amazon and use "a" as the keyword. Now, you can perform Amazon searches by typing the following into the URL bar of Firefox from any page:
without the quotes. This one would search Amazon.com for the word "apple."
You can do this with literally any page that has text form fields. This is extremely powerful.
If you read my blog semi-regularly, you may have noticed that one of my major themes is using the keyboard as the main input device - i.e. I am not crazy about the mouse and I don't like to take my hands of the keyboard. Learning about this technology is a major leap forward for me in this regard.
I hope you enjoy this one. I think it's huge.