I've got a list that includes every "f" key and what it's used to....

F1

• Almost always used as the help key, almost every program will open the help screen when this key is pressed.

• Enter CMOS setup.
  

• Windows key + F1 would open the Microsoft Windows help and support center.
• Open the Task pane.
  

• In Windows renames a highlighted icon, file or folder in all versions of Windows.
• Alt + Ctrl + F2 opens document window in Microsoft word.
  
• Ctrl + F2 displays the print preview window in Microsoft Word.
• Quickly rename a selected file or folder.
• Enter CMOS setup.
  

• Often opens a search feature for many programs including Microsoft Windows when at the Windows Desktop.
  
• In MS-DOS or Windows command line F3 will repeat the last command.
• Shift + F3 will change the text in Microsoft Word from upper to lower case or a capital letter at the beginning of every word.
• Windows key + F3 opens the Advanced find window in Microsoft Outlook.
• Open Mission control on an Apple computer running Mac OS X.

• Open find window in Windows 95 to XP.
• Open the adress bar in Windows Explorer and Internet Explorer.
  
• Repeat the last action performed (Word 2000+)
• Alt + F4 will close the program window currently active in Microsoft Windows.
• Ctrl + F4 will close the open window within the current active window in Microsoft Windows.

• In all modern Internet Browsers pressing F5 will refresh or reload the page or document window.
• Open the find, replace, and go to window in Microsoft Word.
• Starts a slideshow in PowerPoint.

• Move the cursor to the Adress bar in Internet Explorer, Mozilla firefox and most other Internet browsers.
• Ctrl + Shift + F6 opens to another open Microsoft Word document.

• Commonly used to spell check and grammar check a document in Microsoft programs such as Microsoft Word, Outlook, etc.
• Shift + F7 runs a Thesaurus check on the word highlighted.
• Turns on Caret browsing in Mozilla Firefox.

• Function key used to enter the Windows startup menu, commonly used to access Windows Safe mode.

• Opens the Measurements toolbar in Quark 5.0.
• With Mac OS 10.3 or later shows all open Windows.
• Using the Fn key and F9 at the same time will open Mission Control on an Apple computer running Mac OS X.

• In Microsoft Windows activates the menu bar of an open application.
• Shift + F10 is the same as right clicking on a highlighted icon, file, or Internet link.
• Access the hidden recovery partition on HP and Sony computers.
• Enter CMOS setup.
  
• With Mac OS 10.3 or later shows all open Windows for active program.

• Full-screen mode in all modern Internet browsers.
• Ctrl + F11 as computer is starting to access the hiden recovery partition on many Dell computers.
• Access the hidden recovery partition on eMachines, Gateway, and Lenovo computers.
• With Mac OS 10.4 or later hides all open windows and shows the Desktop.

• Open the Save as window in Microsoft Word.
• Shift + F12 save the Microsoft Word document.
• Ctrl + Shift + F12 prints a document in Microsoft Word.
• Preview a page in Microsoft Expression Web
• Open Firebug.
  
• With an Apple running Mac OS 10.4 or later F12 will show or hides the Dashboard.