Here's an idea, an operating system (really just a GUI) built around productivity principles and meant to maximize the happiness and effectiveness of those who have trouble focusing, on those who tend to procrastinate, and on those whose minds tend to wander.
In some ways, a typical modern OS allows too much freedom -- so it's possible to read Boing Boing while intending to study calculus, for example. What I would like to see is an interface that does more guiding. Obviously, as the user, you have the power to override it but the point would be that if you wanted to study instead of surf, it wouldn't be too easy to surf.
Instead, you get a full screen that allows you to navigate through what it is you actually want to do but keeps you away from temptation.