I really like the simplicity of this. I find myself doing the same thing sometimes, e.g. opening HN almost unconsciously and then closing the tab immediately. Who knows, this might help break the habit!

Edit: (A simple suggestion that comes down to personal taste) It would be cool if I could see if I have DistractOff set to 'Stop' by just looking at the icon (in a similar fashion to how adblock shows the status via its icon) so I don't have to click into the plugin to see if it's on. But like I said, that comes down to personal taste.