While many people use keyboard shortcuts there are a lot of users who aren't aware of them. Here are a few of them for Firefox:
Go Full Screen. Hit F11 to display a page in full screen mode. Hit F11 again to return to normal size.
Bookmark. Hit Ctrl+D and click OK to add the page you are viewing as a bookmark.
Download Manager. Ctrl+J will pull up the download manager.
Start New Tabs. Hit Ctrl+T to open a new tab. You then enter the URL you want for that tab. Use Ctrl+Tab to switch between tabs.
Here is a link which will give you many more keyboard shortcuts for Firefox as well as Internet Explorer and Opera. You may select Windows, Linux or Mac OS X.
Firefox Help: Keyboard Shortcuts
Browser keyboard shortcuts
Linear Mode
