The antics of the #GamerGate mob are the most well-known (and seem to be the most prevalent), but there are also the so-called "Social Justice Warriors" and, more recently, vicious Trump supporters. For all the good social media does, it has allowed for a lot more ugly behavior too.
Well, thanks to Celeste Ng (who posted the original Tweet) and Daniel Abraham (who retweeted it), I learned about this Google Chrome app that can block both abusive troll-types AND their dog-piling followers. It's called Twitter Block Chain. If an Internet hate mob is coming after you, this will lock them out and you won't have to deal with their crap.
So if Internet pests are so taxing that you're tempted to stop speaking your mind, here's a chance to get rid of them. Although it won't protect against some forms of attack (like doxing), it keeps the verbal abuse and threats away.