Steve Jennings/Getty Images for TechCrunch Famed Silicon Valley investor Ron Conway, Zillow cofounder Rich Barton, and early Facebook employee Jeff Rothschild are among this year's new signatories of the Giving Pledge, thereby agreeing to give the majority of their net worths to charity. This year's 13 additions to the Giving Pledge have a combined net worth of around $40 billion. The Giving Pledge was founded in 2010 by Bill and Melinda Gates and investor Warren Buffet and has since garnered the signatures of over 200 billionaires, including Facebook CEO Mark Zuckerberg and Salesforce CEO Marc Benioff. Still missing from the pledge's signatories is Amazon CEO Jeff Bezos, who is the richest person in the world with a net worth of more than $200 billion.