Social Bookmarking could be one of the best things that ever happened to websites and blogs.
Basically Social Bookmarketing sites allow users to create a set of content bookmarks. These bookmarks are organized by tags, which are (usually) arbitrary words or phrases the user can assign to content. This gives the user a way to classify, rank and organize content using tags. The most popular Social Bookmarking Site is del.ici.ous, which has millions of users.
Social Bookmarking sites have an intrinsic advantage over search engines and other bots people choose what to bookmark rather than relying on a program to categorize and qualify content. There is an implied quality in something that someone has taken the time to select.
Social Bookmarkers read other peoples bookmarks and add them to their own if they like them. There are also RSS feeds so people can see what others are tagging, which I think is really cool, and a textbook example of viral marketing.
About 4% of my referrers this month are del.icio.us related, including .8% off the home page, meaning that people click on my link when they see it pop up in their RSS feed. I get a goodly amount of...