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But when it comes to online research and collaboration, are the usual social bookmarking services really the best possible tool for organizing that flood of online information? If you've bookmarked the same website several times over, or misplaced an important bookmark among a hundred others in your list that share the same tag, the limitations of tagging as an organization tool will be clear. And if you're like me, sometime you'll find a certain bookmark easily enough, only to discover that you can't remember precisely which single sentence it was that made you bookmark the page in the first place!

Diigo.com takes social bookmarking to a new level of usefulness.

For research and writing collaboration, in particular, I'm finding all of this a real time-saver.  Normally, for example, you might point your colleague to a social-bookmarked page you'd like them to read — but then you'll often need to take the time to explain its significance in a separate phone call, chat message or email.