We have a fresh niche social site to talk about, and its making a huge splash. Last week, we saw reports that Pinterest has hit 10 million unique monthly U.S. visits. Reports for the week of January 16, 2012 monitored the site traffic as high as 17 million unique monthly U.S. visits. It’s addicting, it’s social, and it’s driving tons of site traffic. So what is Pinterest? The millions of people using and visiting Pinterest everyday are there to do one of two things: users can share their favorite things, people, thoughts, or ideas from all over the web on virtual “boards”; and a person can monitor their board’s activity or “repin” from the people or brands that they follow. Thanks to a beautiful, constantly refreshing interface, each visit to Pinterest can be equally memorable as it is unique.