I got a fruitcake from skateboard champ Tony Hawk and I’ve regifted it. I was the 6,281st person to do so. This was a virtual fruitcake that is making the rounds on Facebook as part of a charitable campaign.

I happen to agree that the fruitcake is the perennial lousy holiday gift, right up there with the tie. It gets passed around so much that it’s the perfect analogy for spreading word about something through viral marketing.

In this case, Hawk is one of seven celebritites — Yao Ming, Jimmy Johnson, Nicole Richie, Joel Madden of the band Good Charlotte, Ben Roethlisberger and the band Fall Out Boy — who participated in a gift-giving campaign, Re-gift the Fruitcake on Facebook or through the web site www.regiftthefruitcake.com.

There is a serious side to it. You can make a donation to charities via PayPal. Hawk’s own charity, the Tony Hawk Foundation, has given $2.5 million to fund 400 skate parks in low-income areas around the country. eBay’s PayPal will make a $20,000 donation to each celebrity charity as part of the campaign.

“It’s an incentive to get the Facebook generation into philanthropy,” Hawk said. “It encourages people to pass along the message about the charities and donate money.”

Hawk, a skateboarding champion, has his own money to give because he is the celebrity behind Activision Blizzard’s billion-dollar skateboarding game franchise. Since 1999, ten games have been released under the Tony Hawk label. The latest is a Nintendo DS game that has an accelerometer so that you can tilt the handheld player to produce skating motions on the screen. Hawk said that accelerometer-based games are a sign of things to come, but he noted that the iPhone is a little challenged at the moment because it doesn’t have game buttons.

But back to the fruitcake. Facebook has proven to be a great way to spread the word about charities through applications such as Causes, a Facebook app which has raised more than $2.5 million for charities in the past year. I’d expect that this year, even in a tough economy, charities will get greater exposure than ever thanks to these viral marketing campaigns which cost almost nothing.