automatic suggestion of tags to users
It would be much more efficient, if you suggest the user a list of tags that are relevant to his curated hyperlink, than having the user adding no tags at all, because it costs him so much time to think about relevant tags.
It is very easy. You can auto-suggest tags to the user by implementing the Zemanta API: http://www.zemanta.com/demo/
API for the tech people:
A good review of the tech behind it: