Andreessen's vehicle this time around is Ning Inc., a Palo Alto-based startup that he began in 2005 with former banker Gina Bianchini.
After months of fine-tuning, Ning is finally ready to make its big push with a free toolkit designed to make it easy to launch a social network with a few mouse clicks. Ning's package includes all the social networking staples - videos, photos, music, forums, personal profiles and blogs.
Although both MySpace and Facebook have become smash hits by offering the same features, Andreessen is convinced people dislike the big social networks' one-size-fits-all approach. With Ning's products, even technology neophytes can customize social networks around narrowly shared interests, such as a sports team, church group, hobby or TV show.
"This is the next logical step (for social networks)," said Andreessen, 35, who is Ning's chief technology officer and primary financier. Bianchini, who first met Andreessen while working at another startup, is chief executive.
Ning hopes to make money through a combination of advertising and fees for premium services like extra storage space or bandwidth.
Since he got rich in 1999 when AOL bought Netscape for $10 billion, Andreessen has been scouring for the next big thing with little success so far. He has invested in variety of startups and still serves as chairman of Opsware Inc., a software support provider that has been growing rapidly in recent years but still has accumulated nearly $500 million in losses since its 1999 inception.