Welcome back to Baby Breakerdom! This week's quest to uncover budding Rule Breakers finds a better yearbook than the one I had and big bucks for do-gooders.

Great entrepreneurs make old ideas fresh. That's what we have this week with myYearbook, which is a teen site cut from the MySpace mold. Sort of.

Here's the difference. While youths dominate both sites, myYearbook is more than a hangout. The idea, according to teenage founders Dave and Catherine Cook, is to replace the hardbound yearbooks that us old Fools spent way too much on and that now are collecting dust on a shelf somewhere. (Two rooms away, in my case.)

So, instead of signing "K.I.T." -- does anyone actually do that anymore? -- myYearbook lets its members actually stay in touch. Or bully. Or flirt. Or become a secret admirer. It's high school on the Web.

But my favorite part of this story is the humor. From the profile of Dusty, myYearbook's canine vice president of marketing:

"It was young Dusty's idea to come up with the free T-shirt and thong offer. Dusty's favorites include long debates about existentialism and cleaning her own butt. She has outsmarted Dave multiple times and proves to be a key co-founder of the site."

Nobody enjoys a good zinger more than your friendly neighborhood Fool. Except for maybe a few venture capitalists. Last week, U.S. Venture Partners and First Round Capital combined to supply myYearbook with $4.1 million in initial funding.

How will myYearbook make that investment pay off? Advertising, of course. But not just any advertising. The financing press release touts myYearbook as a marketing tool for reaching teens by exposing them to subtle pitches at the site.

That could work. One that grabbed me was the iPod icon on Catherine's page. I let her playlist entertain me as I studied for this story (if you can actually call that studying.) I've no idea if the icon is a pitch for Apple (NASDAQ:AAPL), but, if it is, sweet.

Here's the point: Research from 2005 says that teens spend, on average, at least $45 a week. With an estimated 25.2 million teens in the U.S., that's $1.1 billion spent per week and more than $58 billion spent annually. Wouldn't you want a piece of that market? I would. Add this one to the IPO watch list, Fool.

Next up is MIOX Corporation, which hopes to cash in by making the world a better place. How? By making water safe to drink.

According to the website, MIOX was founded in 1994 after years of patented research that found that mixed oxidants -- a chlorine compound that's made from salt and water and which is produced through electrolysis -- could purify water.

That proved useful to the military early on in the company's life. Today, it's trying to become a supplier of choice everywhere there's a water problem. Systems have been installed in 25 countries thus far.

Venture investors, who committed $14.5 million to the company last week, expect that total to grow rapidly. And well they should. Disease can be most ravaging where clean water is absent. Here in the U.S., in the aftermath of Hurricane Katrina, once-uncommon ailments struck those who had languished for days inside the New Orleans Superdome without clean water.

Although this may be a uniquely terrible occurrence in the United States, it's commonplace in many parts of the world. Recent research says that 3 billion people live in cities today and, of those, 1 billion live in slums without clean water, adequate plumbing, or good housing.

Because of these facts, MIOX isn't just a company to invest in; it's one to root for. That's all for now. See you back here next week when we continue the quest to find the greatest growth.

For more Rule-Breaking Foolishness:

How great is growth? Three of the dozens of stocks in the market-beating Motley Fool Rule Breakers portfolio have more than tripled in two years. Care to find out who they are? Click here to get 30 days of free access to the service.

Fool contributor Tim Beyers, ranked 1,402 out of more than 21,400 in Motley Fool CAPS, is a sucker for growth stocks and a contributor to David's Rule Breakers team. Get the skinny on all the stocks he owns by checking Tim's Fool profile. The Motley Fool's disclosure policy is a rebel on Wall Street.