Controlling Online Procrastination

Y-Combinator just released some new anti-procrastination features on their Hacker News site. The fact that I am currently reading this (and posting a blog entry about it) is direct evidence of the utility of such. Settings like bool noprocrast, int maxvisit, and int minaway control the maximum number of visits and the minutes allowed between visits, before the site blocks your access. Be nice if there was a Firefox plugin or Greasemonkey script that could be tweaked in a similar way for arbitrary sites. I probably need this.