The idea of "tagging" sites, or even pictures as we checked out on flickr is fabulous. It is quick and easy organization. Now I quickly tag sites whenever I find a good source. With Diigo I organized even more by making lists. Each unit for the year has a list. I save resources which can be used to that list, then tag for more details. My lists can very easily be shared with my team members or students who are researching. Diigo even lets me highlight and annotate information!
You can create an educator account through Diigo to easily share with students.
This is a great research assistant. I have admittedly searched public tags to find resources. The time I have saved piggy backing off of the work of others. Let's all help each other and tag tag tag!