34. Paul Allen

Microsoft co-founder

2003-07 Given or Pledged: $283 million
Favored Causes: Arts, health and human services, science
Estimated Lifetime Giving*: $937 million
Net Worth**: $16,800 million
Giving as a Percentage of Net Worth: 6%

Allen's $100 million brain science institute will map out the brain to help solve mysteries of neurological disorders. His foundation is a major funder of arts and cultural events in the Pacific Northwest, including local music festivals and the Experience Music Project museum in Seattle. Other causes supported by the foundation include those related to community development, social change, health and human services, and youth.

*Based on public records and interviews with donors
**Based on the Forbes 400 list and donor information
Data: BusinessWeek, GuideStar, The Chronicle of Philanthropy, The Center on Philanthropy at Indiana University