Adblock Plus - AdBlock Plus is a browser extension for Firefox, Chrome, Opera, and several other popular browsers that prevents intrusive ads like pop-ups and malicious code from appearing on websites you visit.
Twitter Block Chain - Chrome extension to block all followers/following on a page
BlockParty - Real-time voice chat rooms from the creators of turntable.fm
Twitter One Click Block - Add a block button for a simple one click blocking.
Mirror Block - Mirror Block is a browser extension that allows you to block users on Twitter.
NextDNS - Block ads, trackers and malicious websites on all your devices.