Justin Timberlake’s support for his favored charity is worth $9.3 million. Paris Hilton’s? $538. The Daily Beast crunches the numbers to find the real value 50 stars—from Madonna, Oprah, and Bono to Angelina, Bob Dylan, and Prince William—bring to their causes

#20, Jessica Alba
Charity: Declare Yourself
Annual Impact: $520,100

Another new mom embraces children’s charities—in this case, Love Our Children USA. Like J. Lo, Alba was chosen as one of the group’s Moms Who Make a Difference in 2009. Her ad for voter group Declare Yourself showed her naked and her mouth covered with tape. “Only you can silence yourself,â€� the ad read. “Make them hear you. Register to vote now.â€� “I think it is important for young people to be aware of the need we have in this country to get them more active politically,” Alba told People magazine. “People respond to things that are shocking.”

Breakdown: TV ($0), Print ($470,000), Internet ($50,100), Personal donations (undisclosed).

Source: TheDailybeast.com