"Being a niche network was never a goal of this company, from the top on down," he said.

What are five of the most popular mainstream and niche networks for Boomers?

"Advertisers can target in on the niche networks," she said.

This strategy may have mirrored a trend during this time period of creating niche social networks such as social movie site Flixster.

"It's easier for niche networks to tackle it, because their expectations are lower in terms of ratings."

This has grown from two to eight niche networks, including environment, and diversity.

Both niche networks preach tolerance, but reinforce an us-against-the-mainstream isolation.

What are the five most intriguing niche networks?

"When you have niche networks, you're going to have niche stars," Mr. Berger said.

Minti was the first Web 2.0 niche social network to provide parent generated and ranked advice.