You may have seen the AddThis buttons on blogs at some point while surfing the web. It’s a simple, free widget blog owners can add to their site that shows a number of bookmarking options at the end of a blog post (there’s also a feed reader widget for easy RSS subscriptions). Readers can bookmark the post on Digg, Del.icio.us, Stumbleupon, Google Bookmarks, Bluedot and other services with a single click. As an example, we’ve added an AddThis button to the end of this post.