Are you addicted to Facebook? Check Pinterest every 10 minutes? Tweet your heart out instead of finishing that TPS report? You need some SelfControl, a free app that lets you add all of your personal website distractions to a blacklist and set a timer. Until the timer reaches zero, all of those sites will be unavailable, so take care to add the right ones. If you really need some alone time, you can also use the app to set a whitelist, granting you access to only the sites you really need to get your work done.