FWIW, with RescueTime you can create whitelists of the sites you DO want to track. Every other site will come through as "non-whitelisted site" (the site info never hits our servers). You can set goals like "spend less than 1h surfing news" and have RescueTime SMS you when you break them.

But there's no solution out there that your lack of discipline won't conquer.

One good hack is to set it up so that you either starve or are publicly shamed when you procrastinate. So, you could quit your job (thus putting starvation on the line!). Or you could embed a RescueTime graph on your blog and invite people to hassle you about how you spend your time. ;-)