Tagging has been a relatively popular, human-driven method for organically categorizing information on the Web. Users are now accustomed to tagging the content that they are publishing or bookmarking.
However, by design, tagging requires users to have some sort of writing privilege, which greatly limits its reach potential. Practically speaking, it means that if a user wants to tag an item on a system (e.g, Youtube, Flickr, or delicious) he or she must have an account on that system and be logged in at the time of the operation.
While this is probably not an issue for major Internet services, it can be a chicken-and-egg issue for new, upcoming services that do not yet have a large enough community to build a meaningful tag cloud. How can a new service maximize its community tag cloud if it doesn’t yet have a community?