Online Giving Meets Social Networking

LATE last month, tens of thousands of runners who are registered for this year’s New York City Marathon got an e-mail from Mary Wittenberg, the president and chief executive of New York Road Runners.

She implored the runners to join a social networking Web site that Mr. Norton and three partners started in May that she says has the potential to revolutionize charitable giving. It’s called Crowdrise.com.