eBay is among the most popular auction sites, although some groups choose to run their auctions independently. With 147 million users, it reports helping raise more than $40 million for charitable groups since 2000. 2003 saw the creation of Giving Works, a division of eBay specifically for charity, which has sold more than 60,000 items and brought in $6.3 million for 5,245 charities.

Missionfish, a nonprofit group contracted by eBay, checks the nonprofit status of groups that register for the Giving Works program. Legitimate charities then gain such benefits as free registration with eBay and the charitable return of hosting and insertion fees.

No matter how large or small, "any organization with a committed staff who's willing to make it happen can do this," said Elana Viner, program coordinator at the Child Welfare League of America, an umbrella group for 900 child-welfare organization nationwide. In addition to better item prices, online auctions help spread a foundation's recognition to a wider audience, she said. Since April 2004, online auctions have helped CWLA bring in more than $8,000, said Viner.