When it comes to online giving market places, the adage is: If you build it, few will come. So how do you drive enough people to such online spaces to make them work? In this audio lecture, sponsored by the Stanford Center for Social Innovation, William Meehan, McKinsey senior director, talks about the opportunities and challenges in making online giving marketplaces successful, and what lies ahead in this new philanthropy field for organizations dedicated to making a genuine sustained impact in communities.