Mac: We've highlighted several ways to steer clear of time-wasting web sites and reclaim your productivity. Focus is a new utility for Mac users that makes it simple and easy. Tell it the sites you want to avoid, and when you try to visit, it will display a motivational quote to encourage you to get back to work.
Focus sits in the menu bar and runs in the background. Click it to activate it before you set in on your work, and the app will redirect any attempts to visit time-wasting sites (a list that you fill in) to a self-generated page that shows you a motivational quote. In this regard, it's a bit like previously mentioned Chrome extension Time Warp.
The beauty of the app is that you just have to click it to activate or deactivate. No messing around with your hosts file or more complicated manoeuvres required. The app uses OS X's built-in automatic proxy configuration to work, so it doesn't communicate with the web on its own or read your traffic -- it uses your Mac's built-in tools to keep you focused.
There are a few caveats though -- it will block HTTPS sites, but it won't display a message, and there's a Firefox tweak you'll need to apply to get it to work in that browser. Hit the link below to download it (it's free!) and read more about the app and how it was made.