As all social media users know, occasional time spent checking your various web accounts can add up during the day, and not all of it is productive. I use Twitter and Stack Overflow, primarily to help new developers, but the nature of these sites is that a new software library or interesting news story appears in front of you, and before you know it you’ve entered the rabbit-hole. Browser plugins are already available to prevent a user from accessing particular sites (I imagine Facebook to be a particular time-sink) but, for me, this feels like a sledgehammer solution.
I think it would be nicer to write a plugin to count the clicks on the “distraction sites” and to show an estimated amount of time that the user has spent on them during the day. A small graph could be shown to the user for them to see how their usage has fared against other days, perhaps so they can reduce this addictive behaviour (rather than stopping it entirely). I should have a look at the Firefox Add-ons library to see if anyone has worked on any such thing…