Editor's note: Social media has quickly grown from a fun pastime to a serious business tool. And it's not just major corporations or CEOs who are blogging, Facebooking, and YouTubing. Portfolio.com and bizjournals take a look at how nonprofits increasingly turn to this medium as a way to reach audiences they didn't have access to before. Tuesday we began with a look at how smaller organizations are getting wide exposure. Today, we'll see how social media is leading more people to take action for good causes. And Friday, we'll learn about how social networking is encouraging novel forms of grassroots charitable giving and activism.

In February, when blood banks in Texas opened their doors to 16-year-old donors for the first time, the South Texas Blood and Tissue Center needed a marketing strategy to attract the teens.

Never mind traditional television and billboard ads. That’s so yesterday.

Instead, the blood bank hooked up with the students through social-media channel MySpace and tapped into an energetic new generation of donors—yielding 3,000 units collected from 16-year-olds alone.

“We’ve got 662 friends on our MySpace page, 95 percent of them high-school-student donors. They have embraced it wholeheartedly,” says Janice V. Carpio, assistant director of community relations for the center. “A testimonial from one of their peers on MySpace has much more punch than a flyer.”

Indeed, when the STBTC holds blood drives at local high schools (16-year-olds must have parental consent), staff members snap photos and shoot videos of the donors and post them on MySpace. Students are asked to find their photos and videos online and type in a comment. Once a month, the blood bank chooses a comment and awards movie tickets, T-shirts, and assorted swag to the winner. “We make it fun and give them a reason to stay connected with us,” Carpio says.

And it’s not just Generation Y. Through its “Connectforlife” Twitter and Facebook accounts, the blood bank has raised awareness with all ages. When blood, marrow, and stem-cell donors tweet during the process, Carpio and staff find the Twitterbugs, rewarding them with social media T-shirts and hats. When the Fort Hood shooting occurred and the STBTC shipped blood supplies to Killeen, Texas, the agency turned to social media.

“We had over 100 mentions on Twitter involving our location hours, blood supply needs, and other donor related messages. And from November 6 through 8, we saw a 30 percent increase on blood donations and a 41 percent increase on platelets from donors. We were able to replenish our own supply,” Carpio says.

That ability to rally new volunteers and create a loyal community through MySpace, Twitter, and Facebook—all for a little elbow grease and pennies on the dollar—is the reason many nonprofit agencies in San Antonio and worldwide are embracing social media. In fact, charitable organizations in general are outpacing the business world and academia in their use of social media, according to a recent report by the University of Massachusetts Dartmouth Center for Marketing Research.

“In the latest study (2008), a remarkable 89 percent of charitable organizations are using some form of social media, including blogs, podcasts, message boards, social networking, video blogging, and wikis,” the study reports, adding that the use of microblogging tool Twitter and video site YouTube has spiked as well.