This will likely be remedial for the more seasoned, but for the benefit of the rest we wanted to share this most important of all keyboard shortcuts.
To quickly alternate between open windows on your desktop - like from Outlook to Firefox, or Firefox to Word - train your fingers on this sequence:
In Windows this will alternate you between the window you're currently viewing and the last window you had open. I use this all day long, especially when I'm writing emails and need to reference data on an open Excel page or website. Note that holding down the Alt button while pressing Tab repeatedly will allow you to browse through all open programs.
Alt + Tab
Likewise, Mac users have a similar shortcut they can use to access the most recently viewed window:
Hope this speeds up your day, or at the very least gives you a quick way to navigate away from your Facebook profile when the need arises.
Command + Tab