#13 Del.icio.us

This seems to be essentially keyword creation. I can't help thinking that the complete freedom with which you first start adding tags would eventually have to give way to some kind of thesaurus, at the very least, once you start to get a lot of sites bookmarked, otherwise your search tool would become meaningless. It strikes me as a useful adjunct to the hierarchical ordering of a browser favourites folder, but not as a replacement for it. The "social" part of tagging made me a little uneasy, due to the lack of privacy.