Multiple Islamic websites
EFFECT OF ATTACKS:
According to the attackers, "around 8 websites have been taken down, and about ten websites were decimated or covered with [offensive media]." (1)
Anonymous (group of _chan (many), Ebaumsworld, Something Awful, Encyclopedia Dramatica, Partyvan, etc. users)
TYPE OF ATTACK:
Disorganized spam, trolling, unconventional DoS
In addition to planned general griefing, harassment, email/Twitter/website spam, and hacking attempts, a major part of the plan involved unconventional DoS actions. Many forums were rendered practically unusable, having been inundated with anti-Islam media spam over an extended period of time. Another tactic--with unknown success--was the intentional inciting of threats of violence. The threats, if on a site hosted in the United States, would then be reported to appropriate authorities in an effort to have the site taken down. Finally, a customized anti-Islam version of the Last Measure meme was created (a site trolls would link to in the late 90s that would display offensive pictures in an infinite number of browser popups along with very loud offensive audio, all of which eventually crashes the browser or computer).
An "Anonymous" attack on Islam in general in the name of free speech. The impetus was the censoring of South Park after death threats were made against the network and show's creators. Known as Operation Islamichan, the attack was multi-fronted to utilize several methods of harassment and hacking.