Pop quiz: What do Kylie Minogue, Gary Brolsma and the phone company Jamba! have in common?

They've all found fame (and some fortune) in viral videos that people have spread over the internet.

In 2001, sensual lingerie label Agent Provocateur got pop star Kylie Minogue to shed light (and a little clothing!) on its brand in a controversial ad campaign. The video brought massive attention to the brand and is estimated to have been watched at least 360 million times since it first surfaced on the Web!

You might not have heard of the name Gary Brolsma, but it's likely that the 'Numa Numa Dance' may ring a bell. Gary caught the world's attention with a homemade webcam video of himself lip-syncing to an obscure but highly infectious pop song. Since then, Gary has been voted 'The Number 1 Internet Icon' on the VH1 TV network and the video quickly became an Internet phenomenon, racking up an estimated 700 million views.

Jamba! in particular has earned an estimated £14 million from sale of the The Crazy Frog ringtone. Yeah, remember that obnoxious and unmistakable animated frog that annoyed the living daylights out of you? Who would've ever thought something like that could create so much wealth?

Amazingly, the most popular viral videos didn't start out as planned, yet ended up becoming the most talked about stuff on the Web.

Having other people tell your story for you is always more effective than making your sales pitch to an audience. Why? Because it's more authentic.

When was the last time you shared some news with someone or bought something based on a friend's recommendation? Not too long ago, was it?

So imagine what happens when one person shares it with another, and that person shares it with yet another, and on and on. How would you like to have thousands of people selling your products or services for you?

Best thing is, if you have something cool to share, people will want to share it with others - for FREE!

Next: Viral marketing successes