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.
Secateur - Use Secateur if you want to temporarily or permanently block or mute (or both block and mute) a Twitter account and all its followers.
BlockParty - Real-time voice chat rooms from the creators of turntable.fm
Block Together - A useful tool which helps you block trolls on Twitter.
Twitter One Click Block - Add a block button for a simple one click blocking.
NextDNS - Block ads, trackers and malicious websites on all your devices.