Today’s press release from Hitwise lists the top 20 social networking sites for February 2007, and discusses growing sites. Here are some key points:

• The market share of visits to the custom category of the top 20 social networking sites increased by 11.5% from January 2007 to February 2007. Year-over-year (February 2006 – February 2007) category traffic was up 87%.
• Traffic to MySpace was up 10.2% from January to February 2007 and 107.3% year over year.
• Buzznet and IMEEM showed the fastest growth within the category, with visits increasing 148.4% and 145.7% respectively from January to February 2007.
• Other fast growing sites included Hoverspot (up 19.6%) and Bebo (up 17.8%).

While MySpace is still by far the dominant social networking site, capturing more than 80% of visits to the category, the category is still growing at a rapid pace, and the growth of these newer sites shows that it hasn’t yet plateaued. Hitwise custom category clickstream, which will launch tomorrow, shows that as a group, the other 19 social networks on the chart above received 25.8% of their upstream visits from MySpace. In other words, one in four visits to the 19 other leading social networks came directly from MySpace, demonstrating the vast breadth of its influence among users of most of these other sites.