The WarpIt widget was made especially for bloggers. This is different from the Facebook Like or Recommend buttons, different from the Twitter button, and different from the +1 button. The way it works is that you put this little chunk of code on your blog, just like any other plugin or widget, and it allows people to recommend your article or blog entry. Now your blog entry appears as recommended reading to everyone else who fits your demography. The first time you click the button, a survey appears asking you three questions. Based on the responses to those three questions, you will be presented with a list of articles written by other like-minded people in your age group.
This is a more peer-to-peer approach than the "hub" type action of Facebook and Twitter, which depend on the numbers of people in your friends list. Instead, WarpIt sends your article all over the world, to people you would never get to meet. So, when a person in America, Canada, Europe, Africa, or Asia clicks the WarpIt button on an article they like, they are presented with a short list of articles, and your article is in the list.
It is entirely free, and works great in a Serendipity. Also works great in most other blogs. I am a WarpIt co-author and a Serendipity blogger.
Get your WarpIt plugin here: