Alexa is a website that provides information on web traffic and maintains a list of the top 100 most trafficked sites on the web.  Interestingly, the Alexa list of the most visited sites is drastically different today from the list just a few years ago.  Now the most popular sites include relatively new names, such as Myspace (#3), YouTube (4), Facebook (5), Wikipedia (8), Craigslist (10), Blogger (13), Flickr (20), LiveJournal (26), Digg (28), LinkedIn (32), Wordpress (36), and Orkut (40).  Beyond their relative newness, these sites share a common link (no pun intended): all are driven by user interaction and user-submitted content.  Sites based almost entirely on user-input have thrived in recent years.  YouTube (a video sharing site) features about 73 million videos, and MySpace (a social networking site) has 300 million registered users.  According to Bill Tancer, “Wikipedia’s user-created entries have surpassed the 5 million mark.  In 2006 YouTube announced that it had served over 100 million video clips per day.”  However, the era of web interaction originated from humble roots.