[I]n the process of our learning the nature of the real, what we do is to look for some order of a certain general type and, if we do not find that, to look for some other. [Clarence Irving Lewis, **Mind and the World-Order**]
I like to tag, and tag a lot : my del.icio.us links, my citeulike.org references, etc.
Classification systems need to be used to have a meaning. I use them to process information. Hopefully, this processing becomes organization. Since there is always a more lean, fit, or beautiful organization lying around, this process never ends.
So tagging is retagging. Maybe I delete, discard or rename too much. But this guilty pleasure is in the spirit of tagging.
Some tagging systems help me tag again, like Delicious. Some don't, like Citeulike. Some seems to prevent me from doing this, no need to mention them.
Reality shall be orderly, since its uniformity seems somewhat necessary for knowledge. But before we come to underpin the very order or reality, our tools could help analyze and organize, by letting our minds abstract and, more to the point, discard.
If you cannot only try to tag, don't.
PS: Since lots of links are created on-the-fly by tagging, and since tagging is ephemereal, we see that the ideal of eternal links will never obtain. Yet another argument against the hype of links.