Features Rated 4 out of 5 stars
The idea is great, but realization sucks by now(sorry for my english). You wrote in comments that it looks to easy because of the privacy matters. Add then two different politics of surfing, so it will be possible to choose just blocking annoying results, or going into ninja-mode. Or even both of them at once. Besides that you can make black-list editable, but put password on it, so user can be able to see had he already blocked that bunch of sites or not. Eventually, if you are working for privacy that hard, what's the point of "block this" button? Double-mode politic will be the best, imho.
About urls: i tried to block *exaple.com* and my browser crushed. You wrote in comments that it's complicated fragment blocking using scripts that run the addon by now, but can u at least make * definitions acceptable? That+black-list editing feature and addon will stay for its' name. Btw, same fragment blocking can be used for download manager. : )
About Rushis' proposal: idea is great, but if you'll bring it to life, please don't make as a default option. F.e. i like to configure what should be blocked and what should not only manually.
And thank you for your comments, i hope you'll make this addon better, the idea is just too good to pass away.
Good luck and lots of coffee. ;d