Targeted giving --- from Bill Gates to Brad Pitt to the Buffett kids

Fighting for a causeBill and Melinda Gates are giving away billions to find a cure for AIDs, to curb childhood malaria, and to improve computer literacy worldwide among the young.

But what about sisters Helen and Swanee Hunt, daughters of Texas oil magnate H.L. Hunt? They're tapping women across the country to write checks that promote women's health and job-training programs.

Then there's Brad Pitt, who runs the Make It Right Foundation. He's pledged $5 million to help construct 150 new low-income homes in New Orleans.

These rich and famous are on the latest Barron's magazine list of the world's 25 best philanthropists -- based on the results of their charity.

On top is Ebay founder Pierre Omidyar and his wife Pam. They've committed at least $300 million since 2004 to such innovations as Wikipedia.

Others on the list in the Nov. 30 edition of Barron's:

--Howard G. Buffett, oldest son of Berkshire Hathaway tycoon Warren Buffett. Howie has earmarked funds to improve rural water supplies in 13 countries.

--Peter and Jennifer Buffett. Warren's youngest son and his wife are focusing their philanthropy on helping women and girls in developing nations.