Diigo is the tagging and social bookmarking site. Registered Diigo users can bookmark, tag and highlight webpages with the key feature of adding annotations. For collaborative projects, you can share those annotations with a group or create a share link to send to outside users. The social tagging feature has created a collection of quality content with the opportunity to find and connect with those with shared interests in the field.
Diigo
Watch this video about using Diigo to collect, highlight and select. (3 min. 36 sec.)
Apply for a Diigo Educator Upgrade to request a special premium account provided specifically to educators.
Note: To get quick access to your Diigo libraries and be able to quickly bookmark, highlight and annotate webpages, consider installing the Diigo Toolbar in your browser.