When I first explained my punishment kink to my godfather (I have an, um, unique relationship with my godfather as I explain in this post), the first words out his lips were, "what a convenient kink!"
As this article in the New Yorker demonstrates, people do all sorts of stuff to help with their procrastination issues. It reminded me that it is a rare person indeed who needs no assistance with self-discipline.
We, of course, include hairbrushes and canes, in addition to software, to limit our time on Facebook.