Yesterday the top upvoted comment for "Why We Desperately Need a New (and Better) Google" http://news.ycombinator.com/item?id=2057772 was adding personal domain blacklists. I offered to build this if there was enough interest so here's a minimum viable product for Chrome (Firefox soon to follow): https://chrome.google.com/extensions/detail/jiicbcimbjppjbckmoknagndlhjbeohb. Your feedback is welcome!