DISCLAIMER
I am not talking about Jacob Appelbaum, though I don't approve the creation of http://jacobappelbaum.net even if the stories are real. I don't know him neither any of the people involved. I am not expressing any opinion about this case. This steps are generic.
STEPS
Find a person that is famous on the internet as a target. It can be because of his work, his activism or whatever.
Create a story that "could be real". For example, check some places where the target has been and the people it has been with. Then add some lies on top of that to create a gruesome story, the more gruesome, the better. Stories with sexual content and difficult to prove allegations are the best.
Submit to a popular blog, anonymously. The ones that publish anything would work, like any of the Gawker media. Submit with a PGP key that you just created, just to be able to follow up anonymously and look professional in the anonymity world. Don't worry, people do not care about the presumption of innocence.
You can even invent several stories and submit them with several different "anonymous identities" that you just created. Just be sure you do it through the TOR network.
Create a webpage that harrasses the intended person, creates impact and can be easily shared by copypasting a URL. Everything can be anonymous.
For most impact create a hashtag that allow people to share easily content and follow. Buy some fake accounts to create impact or just convince some "counter activists" to share the story. The more tight is the activist group and the more religious and contrary to the story their ideology, the better, as they will fight harder.
The ball will grow until it explodes. Remember to silence everybody that can prove the falseness of the story by burying into the indifference and arguing that they are defending something very undesirable. Obviate the presumption of innocence and say that they are becoming criminals by defending a criminal or even by defending his right to defend himself.
Even if everything is proven false some weeks or months after, the reputation of that person is already destroyed. Some side effects can happen: the target can lose its job or its family.
Obviously you would have committed several crimes during the process, but it is unlikely that you will be prosecuted. It is very typical that the person chooses to hide until the shit goes away, so they will avoid any further action.