Netscape cofounder and Mosaic coauthor Marc Andreessen joined Facebook’s Board of Directors on July 1. Andreessen is currently the chief technology officer of Ning (www.ning.com), a social-network creation platform provider. Ning lets users create their own customizable online social networks.

Netscape Communications was acquired by AOL in 1998 for a reported $4.2 billion. Andreessen served as AOL’s CTO for a while after the acquisition, and then cofounded Loudcloud, later named Opsware, which was acquired by Hewlett-Packard in 2007 for a reported $1.6 billion. Loudcloud was a web infrastructure company.

Andreessen appeared on the cover of Time magazine’s February 19, 1996, issue as one of “The Golden Geeks,” the tech wunderkids that started technology companies in the mid-to-late 1990s and made billions in the stock markets. He holds the distinction of being one of only a few people to start two companies and sell both for over $1 billion.