The Combating Terrorism Center at West Point (the U.S. Army military academy) has published an analysis of the use of online social networks by Jihadists and their effectiveness in recruiting.
The article provides an excellent summary of how use, rather than misuse, of the Internet appears to be more important to most extremists:
In the same way that traditional terrorist training camps once served as beacons for would-be jihadists, online support forums such as Muntada al-Ansar and al-Ekhlaas now operate as black holes in cyberspace, drawing in and indoctrinating sympathetic recruits, teaching them basic military skills and providing a web of social contacts that bridges directly into the ranks of al-Qa`ida. Rather than simply using the web as a weapon to destroy the infrastructure of their enemies, al-Qa`ida is using it instead as a logistical tool to revolutionize the process of terrorist enlistment and training." "This is the hidden dark side of online social-networking—as a virtual factory for the production of terrorists."Al-Qa`ida’s “MySpace”: Terrorist Recruitment on the Internet
The same issue (January 2008) also contains an article discussing Al-Qaeda's extensive use of the Internet (see Al-Qaeda and the Internet)