Let's have a website, where you can ask any question. This question has to go in appropriate cateogry for people to answer. Let's have set of keywords from which you can select for your question. Based on the keywords, question can appear in multiple categories. Other users (on certain level) are also allowed to assign a keyword for your question. You or other user can even propose a new keyword ( which is not approved yet) for the question. There is a group of people who approves new keywords. Keywords can constantly be refined, so that you can only assign specific keywords. There could be 'approved keywords system' for the 'general terms'
.... and so on..-- artist, Jul 21 2003 this is very similar to how 'interests' are handled on systems such as livejournal and friendster. You can add most anything you want as an interest and anyone who adds like terms will both have a shared interest. There is an approved list of interests that help prevent people from calling the same interest by fragmented names though the approved list is easily edited.-- ry4an, Jul 21 2003 random, halfbakery