• Learn how an alternate reality game for Halo 2 received 240,000 visitors on its debut

• Find out how The Big Word Project achieved worldwide publicity with almost zero cost

• Discover how The Blair Witch Project became the largest per-screen gross in motion-picture history

If you are a digital marketing agency searching for the top viral campaigns to emulate, you've found them. Read on and learn from these success stories.

1) I Love Bees

“I Love Bees” was an alternate reality game that was part of the viral campaign for the release of popular first-person shooter game, Halo 2.

Advertised by a subliminal message in Halo 2 trailer, players who logged onto the website discovered that the pages seemed to be hacked by a mysterious intelligence. This is part of the elaborate website design aimed to heighten the users' sense of curiosity and urge them to probe deeper into this complex website.

As players solved puzzles, they eventually discovered audio logs posted on the website that gradually revealed more of the fictional background story, involving an artificial intelligence left behind on planet Earth and its attempts at putting itself back together.

The reception that the campaign received was phenomenal. The website received over three million unique visitors over the course of three months. At least 250,000 fans logged onto the site on the day of its debut, and more than 500,000 returned to the site each day it was updated.

2) The Big Word Project

Not all viral campaigns are carried out by large production companies to gain commercial success. Two Masters students from Northern Ireland have developed a project aimed at exploring what different words mean to different people.

Anyone who visited their website are given the opportunity to buy a word from a list of over 170,000 at $1 a letter, and that word is then permanently linked to a URL of their choice. Although having a link on the site might not increase search engine optimisation for someone attempting to promote his website, it can still increase website traffic.

Although both students are web designers, the site was created with a simplistic web 2.0-style with few colours and no advertisements. There was virtually no cost involved in the making of this project.

Even so, The Big Word Project saw thousands of visitors in just the first week and had to add more than 2,000 words to the list to meet growing demands. The word count has passed 5,000 since its launch.

The website became popular purely due to word-of-mouth, primarily bloggers, spreading the word throughout the internet. All proceeds from the project have gone towards paying their tuition fees.

3) The Blair Witch Project

The technique of viral marketing was initially popularised by the successful marketing campaign for The Blair Witch Project, a tiny budget film, which set a record for the largest per-screen gross in motion-picture history.

Released in 1999, this low budget movie captures the story of three young student filmmakers who disappeared in the forest while filming a documentary about a local legend called the Blair Witch. The video was supposedly recovered a year later without any trace of the students or their bodies.

The film generated plenty of buzz online as the creators created a myth that they had found actual footage of an unexplainable phenomenon left by a missing group of campers. The creators themselves seeded this myth by appearing on a television show with 8 minutes of footage they claimed was found in the woods. When The Blair Witch Project website went live, they further spread this disinformation.

Since the World Wide Web was still developing during that time, the average internet audience was less used to subtle marketing strategies. With the attention of conventional media adding in to the hype, the result was a profit of around $300million, in front of a total cost of less than $3million.

Although all of these viral campaigns are different, they were still invested in internet search marketing and came out tops during their respective heyday. That should be the goal of every viral campaign.