Irwin from Microsoft Live Favorites gives this quote on tagging.
“Think about it, if I tag things that interest me in a meaninful way to me, and then I tag myself with what I’m like, and then everyone else does that, we can do really cool stuff like “Get me information on photography that other peope like me are looking at”. Then filter that further by other tags on those people or topics. Then subscribe to a feed of that via RSS. Now I have a highly customized feed of information on a topic I like that “experts” (to me) are providing me with. Then I turn around, put my own tags on it and spin on it, and I become part of that network as people rely on me for the same filtering that my experts do. That’s an amazing experience right there.”
I like the thinking here though I am a little unsure about after receiving the link to tag it with a different set of tags, I may add a tag or two to it but nine times out of ten I would never remove a tag from the source unless it was an industry specific type tag.
eg. “healthcare+microsoft+windows+xp” I would drop the ‘healthcare’ tag as I would not need that for my tagging in the computing industry