Many Facebook users are not aware of the keyboard shortcuts FB provided for their users. I have listed few keyboard shortcuts below, among them few are browser dependent but not all.
Friend requests Page [Browser Dependent]
Internet Explorer for PC: Alt + #, then Enter
Firefox for PC: Shift + Alt + #
Safari for Mac: Ctrl + Opt + #
Firefox for Mac: Ctrl + Opt + #
Chrome for Mac: Ctrl + Opt + #
Chrome for PC: Alt + #
Keyboard Shortcuts
c - Comment when on a story in News Feed
j and k - Scroll between News Feed stories
l - like or unlike a selected story
q - search for a friend to chat with
p - Focus on the text box when making a post
/ - Search