Those that use Chrome or Opera may be used to the autocomplete feature in the address bar, and have wished for such a feature in Firefox as well.
Sure, Firefox has the "Awesome Bar", but autocomplete would be cool
Well, here's how:
First, open a new tab in Firefox, then type about:config
into the address bar, and hit enter.
Click the "Yes, I'll be careful" when you reach the page warning you of strange and dangerous mythical creatures or warranty voiding whatnot.
Then, type browser.urlbar.autoFill
into the search bar on the page, hit enter, and then double click the first entry in the list.
Firefox will then start completing URLs for you
Note that for many addresses you may have to type the www. before the next letters, but, it's still a cool hack.
For me, it's back to Opera I go, but this may make you switch.
Source: Enigma Community Guides