Excellent tool. Only thing probably missing is a 'temporary unblock' feature where the user can unblock a site for only a couple of minutes after the time limit has been reached. The attempts for temporary unblocking can be specified or be set by default.

Edit: Thanks for the reply. This deserves an additional star.

I install this when I want to be productive.

Self control has never been easier.

This is the best add on to keep us away from distractions specially for student like me this helps a lot as we can set the timing and day for such distractions and even have daily limit for use of such websites