According to a new survey social networks attract nearly half of all web users:

The number of visitors to the top 10 social-networking sites soared in April, attracting nearly half of all Web users, a market research firm says.

The top 10 sites collectively grew 47 percent in the United States from the same month a year ago to 68.8 million unique visitors, Nielsen/NetRatings said. The sites reached 45 percent of active Web users.

The top five sites are MySpace, Blogger, Classmates Online, YouTube, and MSN Spaces.