From their site: a place to keep links to the articles you read and the websites you use, and a place to find them again. It is also a place where you can discover new articles and websites through sharing your links with other users. By saving your links and references to Connotea they are instantly on the web, which means that they are available to you from any computer and that you can point your friends and colleagues to them. In Connotea, every user's links are visible both to visitors and to every other user, and different users' libraries are linked together through the use of common tags or common bookmarks.
Thanks to Dermgal for referencing this site.