Which Web 2.0 tool did I explore, and how might it be used in the classroom to promote communication and/or reflection?

Which Web 2.0 tool did I explore, and how might it be used in the classroom to promote communication and/or reflection? 

In this class, I explored and signed up for the Diigo Web 2.0 tool.  It is used for online bookmarking, highlighting and sticky notes for your readings, it is used for group based collaborative research, and to collect and organize anything anywhere. So, it definitely can be used in the classroom for a collaborative group project in which students have to do researching.  The Diigo allows users to collect, highlight, access, and share a variety of information on a variety of devices.  I certainly see the idea and not so distant future in which an annotated bibliography is not needed.  Why go through all the trouble when you can just use the Diigo Web 2.0 tool?