Firefox is one of the most popular Web browsers, but it's not always one of the most spacious, especially if you use a toolbar or keep a lot of icons in your customized Firefox bar. To grab a little screen space back, try the free Firefox theme Littlefox, which shrinks most of Firefox's menus to give you more room to browse. It saves a considerable amount of space, but a rough and retro style give it a bit of a dated appearance.
Once you install Littlefox and restart the browser, the space gain is immediately noticeable. It trims about a half an inch or more from the top of your browser, giving you more room to work. It also makes any toolbars on your browser smaller. Everything you need to access the toolbars you do use is still available -- just smaller. Unfortunately, Littlefox makes the top part of Firefox look very dated. Think 1998 Netscape. The juxtaposition of that aesthetic with the sleek look of modern Web sites is a bit distracting.
Although it's in dire need of a graphics refresh and additional methods for customizing the interface, Littlefox is still a great add-on for Firefox. If you already use Firefox as your main browser and you are greedy for more screen real estate, try Littlefox to reclaim every little pixel you can.