I often use Safari, and I will type in Command+L to put my cursor in the address bar. Then, I will type in a url without all of the extra stuff like "http" and the ".com" or ".org". I would simply type 'webmasterworld' and I am taken to the correct place.
But, in FireFox, the default is something else...don't know if it is a .org or if it searches for that text...either way, I want to change that to where it will fill in the 'http://', the typed text, and '.com'.
The Fx behaviour is to perform a Google "I'm feeling lucky" search to find the most likely website. Version 2.0 (currently in beta) behaves in a similar way for popular websites, and displays Google search results if the intended URL is not clear-cut.
You can automatically top and tail with "www" and ".com" by pressing ctrl+enter to go to the address.