Diigo (DEE-go) is a Social bookmarking website which allows signed-up users to bookmark and tag web-pages. In that case, it is similar to Delicious, however, Diigo additionally allows users to highlight any part of a webpage and attach sticky notes to specific highlights or to a whole page. These annotatations 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”.
Read more about Diigo and watch a demo video clip here: http://www.diigo.com/
