I’m reminded of this every time I try to retrieve a bookmark from del.icio.us: tags are for the community, not for you.
No really. Every time I go looking for a link from a few months back I search a tag that I *know* I must have tagged it with. A tag that I always tag stuff like that with.
Nine times out of ten I forgot to use that tag, whatever it was. They’re really usless for information retireval. But they sure do help out the community.