Diigo (DEE-go) is a Social bookmarking website which allows signed-up users to bookmark and tag web-pages. Additionally, it allows users to highlight any part of a webpage and attach sticky notes to specific highlights or to a whole page. These annotations can be kept private, shared with a group within Diigo or a special link forwarded to someone else. The name “Diigo” is an abbreviation for “Digest of Internet Information, Groups and Other stuff”.
It was easy to sign up and there is an option to join diigo as a face book application and only took me a few minutes to have the toolbar downloaded.
I have the perfect article to test however you will not be able to read my highlighted comments unless you have downloaded the diigo toolbar.