Excelbook is an Adobe Air based application which you can use to browse Facebook at work without being caught by your boss. The interface can be easily mistaken for an MS Excel or Libre Spreadsheet. You can login to your Facebook account and get all important updates, while appearing to work on a regular task. To get started, login to your Facebook account from the File menu and allow access to Excelbook application from your Facebook account.
Please note that we will not be responsible if you get fired by your angry boss. Use it at your own risk.
Once done, you will be able to view your News Feed, Wall and Chat with friends from the three available tab on the bottom of the interface. You can even rename the sheet titles according to your liking to further disguise the application. The only downside of this app is its most unique feature i.e. the Excel like interface which does not provide any imagery. During testing I also faced problems logging in the second time I launched Excelbook.
In case you would like to instantly hide active program windows from your boss and replace them with your desired application like Excel sheets, check out Magic Boss Key. Being an Adobe Air based app, Excelbook works with Windows XP, Windows Vista, Windows 7, Mac and Linux based operating systems.