The Economist reviews a few apps which are meant to help you focus. I’ve tried some of these but they never really stuck. But you know what the best anti-distraction piece of software I’ve ever used is?
My iPad’s OS.
All tasks are done in full-screen mode: checking email, reading in Instapaper, writing notes in Simplenote, or whatever. And to switch to another app I have to click the home button, look for the other app’s icon, and tap it. Not exactly an arduous process, but also not as easy as a quick press of Command+Tab using my thumb and ring finger.
I’m sure there is more to it than just the app-switching process. But there is no doubt that when using my iPad (regardless of if it’s for work or leisure), I am significantly less prone to distraction or multitasking than when I am using my MacBook Pro.