Micro-blogging site Twitter hasn't been given a grade by the international human rights organization because "they haven't even shown up to the dance yet," said Rabbi Abraham Cooper, head of the centre's annual digital terror and hate project.
"Five years ago, we were essentially talking about websites," Cooper said of the recently released report.
"Now most of the focus has to be on social networking and watching how every wrinkle unfolds."
Facebook earned a high mark because it has taken down thousands of pages that the digital terrorism and hate project has brought to its attention, Cooper said from Los Angeles.
It got an A minus instead of an A because of its more "nuanced" approach to discussion forums, about the denial of the Holocaust, for example, he said.
As for YouTube, Cooper said there's just too many videos about how to carry out terrorist acts.
"That stuff doesn't belong on YouTube, it doesn't belong on the Internet. They could and should do a much better job at setting up and policing their own rules."
Twitter didn't get a grade but Cooper said the site should look more at how it's being utilized. In some cases, it's being used by terrorists for command and control of actual events, he said. In Yemen, information about U.S. drone attacks has been tweeted.
The growth potential for pro-hate and terrorist activity on social networking sites is exponential, he said.
"What was once something that four or five people would see, now 20,000 or 30,000 people might see."
The Simon Wiesenthal Center now has a password-sensitive software application to be used by law enforcement and government agencies to give them real-time access to its digital terrorism and hate project.
"There are now over 15,000 problematic sites," said Cooper, who recently presented the findings of the 14th annual global digital terror and project to officials from the Canadian Security Intelligence Service in Ottawa.
He estimated there may be a few dozen websites of concern in Canada, including a jihadist forum with pictures of Canadian soldiers killed in Afghanistan.
Sociology Prof. Vincent Mosco said much attention has been given to how FaceBook and other social networking sites can be used to advance democracy, but the darker side tends to be neglected.
"Hate groups tend to use these networks given that the consequences are minimal," said Mosco, professor emeritus at Queen's University in Kingston, Ont.
Mosco said hate groups used radio and television before regulations were put in place to prevent them from doing so.
"Why do we tolerate on Facebook what we don't tolerate on TV?" he asked. "I suspect this will evolve over time with a more responsible kind of activity but it does involve informing people about all sides of the 'Net."
The difficulty is that social media transcends borders, making it more difficult to regulate, he said.
"Networks can be used for all sorts of things from advancing the need for democracy to human trafficking. Both of those, one for good, and one for evil, are prominent on the 'Net. It seems to me we need to do something about the latter as well as brag about the former."
What also worries Cooper is what he calls the "lone wolf," someone who finds a community for his beliefs online but acts alone, such as the so-called "underwear bomber" who was convicted of trying to set off plastic explosives on board a plane to Detroit on Dec. 25, 2009.
"That today is the biggest challenge across the board both in terms of obviously terrorism but in terms of hate crime."
Cooper urges parents to know what their kids are doing online.
"They're both the main targets for recruitment and they are the people who have the least in terms of their experience and sophistication and are the most vulnerable."