Do you feel that Facebook is nibbling away at your attention span? Do you find yourself checking status updates when you should be studying for the chemistry exam? There's an app for that - or at least a browser extension that will help you focus.
For Firefox users, the Leechblock add-on will let you set up a list of sites that you want to block during certain times during the day or that you want to limit to a limited amount of time - such as "I'll spend no more than five minutes on Facebook every hour."
For Safari users, try the WasteNoTime extension, recommended by a student in the Simple Living First Term Seminar.
And by the way, if you want tips on how to simplify your life and why you should, that class has published a lot of excellent advice and researched background papers.