History of Anonymous Hacktivism

We are Anonymous. We are legion. We do not forgive. We do not forget. Expect us.

Long before they became vigilantes in the Wikileaks cyberwars, Anonymous was conducting large-scale “raids” against their enemies.

The Habbo Hotel raids

Probably the first time 4chan users banded together under the moniker Anonymous was in order to harass the users of Habbo Hotel, a cartoonish social network designed as a virtual hotel.
As early as 2006, Anonymous would "raid" Habbo, blocking its usual users from moving around. The first major raid is known as the "Great Habbo Raid of '06," and a subsequent raid the following year is known as the "Great Habbo Raid of '07."There appears to be some connection to the news of an Alabama amusement park banning a two-year-old toddler affected by AIDS from entering the park's swimming pool.

Habbo Hotel

Users signed up to the Habbo site dressed in avatars of a black man wearing a grey suit and an Afro hairstyle and blocked entry to the pool, declaring that it was "closed due to AIDS," flooding the site with internet sayings, and forming swastika-like formations. Then when all their black cartoon avatars got banned, they'd call Habbo racist. This was all done "for the lulz," or just for fun.
At this point, Anonymous’ actions had not taken on a political bent. Some members of Anon would argue it was better that way.

Hal Turner

Anonymous targeted this white supremacist with a talk radio show in December 2006. According to Hal Turner, in December 2006 and January 2007 individuals who identified themselves as Anonymous overloaded his website, costing him thousands of dollars in bandwidth bills.
Some Anons seem to have distaste for actual racism, though they express it frequently in jest. But of course you can never tell if it's the same people. "Anon is legion," they like to say.
As a result, Turner sued 4chan, eBaum's World, 7chan, and other websites for copyright infringement. He lost his plea for an injunction, however, and failed to receive letters from the court, which caused the lawsuit to lapse.

Chris Forcand

Anonymous helped catch an internet child predator, Chris Forcand, by reporting information to the police in 2007. By this time, Anonymous began to see themselves as a group of internet vigilantes fighting for assorted noble causes, rather than a band of merry pranksters.
On December 7, 2007, the Canada-based Toronto Sun newspaper published a report stating that Forcand was already being tracked by "cyber-vigilantes who seek to out anyone who presents with a sexual interest in children" before police investigations commenced. Forcand, 53, was charged with two counts of luring a child under the age of 14, attempt to invite sexual touching, attempted exposure, possessing a dangerous weapon, and carrying a concealed weapon
Anonymous contacted the police after some members were "propositioned" by Forcand with "disgusting photos of himself." The report also stated that this is the first time a suspected Internet predator was arrested by the police as a result of Internet vigilantism

The Church of Scientology

With these raids, Anonymous exploded into popular culture. The group gained worldwide press for Project Chanology, the protest against the Church of Scientology. 
On January 14, 2008, a video produced by the Church featuring an interview with Tom Cruise was leaked to the Internet and uploaded to YouTube. When the Church tried to get this embarrassing footage taken down from YouTube, Anonymous formed a splinter group called Project Chanology that dedicated itself to stopping censorship and harassing the exploitative church.
Calling the action by the Church of Scientology a form of Internet censorship, members of Project Chanology organized a series of denial-of-service attacks against Scientology websites, prank calls, and black faxes to Scientology centers.

There were also several organized protests in many cities worldwide against Scientology. They took to the streets, protesting outside of Scientologist churches wearing "V-masks," the disguise used by Alan Moore's vigilante comic book hero, V, originally inspired by would-be British terrorist and folk hero Guy Fawkes.

Epilepsy Foundation

Anonymous has also trolled the Epilepsy Foundation of America, uploading seizure-inducing content to its forums.
On March 28, 2008, the epilepsy support forum run by the Epilepsy Foundation of America was assaulted and JavaScript code and flashing computer animations were posted with the intention of triggering migraine headaches and seizures in photosensitive and pattern-sensitive epileptics.

SOHH and AllHipHop

In late June 2008, users who identified themselves as Anonymous claimed responsibility for a series of attacks against the SOHH (Support Online Hip Hop) website. The attack was reported to have begun in retaliation for insults made by members of SOHH's "Just Bugging Out" forum against 4chan's users.

The attack against the website took place in stages, as Anonymous users flooded the SOHH forums, which were then shut down. On June 23, 2008, the group which identified themselves as Anonymous organized DDoS attacks against the website, successfully eliminating over 60% of the website's service capacity. On June 27, 2008, the hackers utilized cross-site scripting to alter the website's main page with satirical images and headlines referencing numerous racial stereotypes and slurs, and also successfully stole information from SOHH employees.

No Cussing Club

Anonymous also targeted the kid who started The No-Cussing Club, for obvious reasons. In January 2009 members of Anonymous targeted California teen McKay Hatch who runs the No Cussing Club, a website against profanity.

As Hatch's home address, phone number, and other personal information were leaked on-line, his family has received a lot of hate mail, lots of obscene phone calls, and even bogus pizza and pornography deliveries.

YouTube porn day

On May 20, 2009, members of Anonymous uploaded numerous pornographic videos onto YouTube. Many of these videos were disguised as children's videos or family friendly videos with tags such as "jonas brothers." YouTube has since removed all videos uploaded.

The BBC contacted one of the uploaders who stated that it was a "4chan raid" organized due to the removal of music videos from YouTube. BBC News reported that one victim posted a comment saying: "I'm 12 years old and what is this?" which went on to become an internet meme.

Iranian Election protests

Following allegations of vote rigging after the results of the June 2009 Iranian presidential election were announced, declaring Iran's incumbent President Mahmoud Ahmadinejad as the winner, thousands of Iranians participated in demonstrations.

Persian Bay

Anonymous teamed up with Pirate Bay and various Iranian hackers to offer Iranian dissidents a way to plan demonstrations and connect with the outside world. The result was Anonymous Iran, an Iranian Green Party Support site and a successful information-freedom project.

The site has drawn over 22,000 supporters worldwide and allows for information exchange between the world and Iran, despite attempts by the Iranian government to censor news about the riots on the internet. The site offers Iranian activists tools and advice on how to remain anonymous and avoid detection. Forums are provided for coordinating activities and communicating with the west.

Operation Didgeridie

In September 2009 the group reawakened "in order to protect civil rights" after several governments began to block access to its imageboards. The tipping point was the Australian government's plans for ISP-level censorship of the internet.

Early in the evening of September 9, Anonymous took down the prime minister's website with a distributed denial-of-service attack. The site was taken offline for approximately one hour.

Operation Titstorm

On the morning of February 10, 2010, Anonymous launched a more prepared attack hilariously-titled "Operation Titstorm."

It defaced the prime minister's website, took down the Australian Parliament House website for three days and nearly managed to take down the Department of Communications' website as a protest against the Australian Government over the forthcoming internet filtering legislation and the perceived censorship in pornography of small-breasted women (who are perceived to be under age) and female ejaculation.

Other entities they’ve tangled with include AT&T, Gene Simmons, KnowYourMeme, Hot Topic, Jessi Slaughter, and Tumblr. but I would consider these to be only skirmishes.

All of these without mentioning the recent Operation Payback, and the strikes againt Tunisia, Zimbabwe and Egypt.

Who knows where the next target might be...