"Helping to end world hunger."

It's a tall order. Many of us have poured pennies into those little UNICEF collection boxes, or collected soda can tabs, or sponsored friends in walk events. All with the goal of ending world hunger.

But how much does that actually cost? Is it even achievable?

According to United Nations' estimates, "the cost to end world hunger completely, along with diseases related to hunger and poverty, is about $195 billion a year."

So how are we, with our little boxes of coins, bags of soda tabs and $10 pledges going to make a dent in a problem of that size?

Well, the team at freerice.com has figured out one solution. At their site, they have created a simple way of giving everyone a way to help, one click at a time.

When you go to the site (do it now; I'll wait), you see a vocabulary word and a list of four possible synonyms. When you click on the right answer, you win 20 grains of free rice that will be donated to communities in developing countries. For each right answer, 20 more grains are donated.

That's it. You don't need to subscribe to anything. You can stop playing whenever you want. And no one will spam you afterwards.

So what's the big deal? The big deal is that FreeRice.com is the quintessential viral marketing success story. Word is spreading from friend to friend, family member to family member, teacher to teacher, and everyone is playing along.

Here are the numbers:

• According to the site, more than 28 billion (with a "b") grains of rice have been donated since the site was launched in October 2007.
• Doing the math, that means this nonprofit has received millions of hits to their website in less than a year.

How are they doing it? How is this nonprofit, without spending a large advertising budget, able to get that many visitors?

FreeRice.com has found the perfect combination with a simple message and a clear payoff. Created by one man to help his son learn vocabulary words for his SAT test, this site has a simple premise and delivers on a simple promise: play a game, learn new words and help someone else.

And competitive as we are, who doesn't want to win? FreeRice.com is the definitive win-win.

PS-My personal best is 820 grains of rice...what's yours?