I seem to remember someone posting on Less Wrong about software that locks your computer to only doing certain tasks for a given period (to fight web-surfing will-power failures, I guess). After some cursory digging on the site, I couldn't find it. Does anybody remember the thread were this kind of self-binding software was discussed or at least the name of some brand of this software?

(Ideally I would like to read the thread first, and get a sense of how well this works.)