Categorize and Tag Users

I’ve hunted high and low for a solution to this, but haven’t found anything even remotely close, so here goes – does anyone have any plans to create a plugin which will let me assign users to categories in the standard category taxonomy, or even just let me tag users? This isn’t to restrict anyone from posting – in some cases, users won’t get further than simply adding their profile – it’s just to enhance searches and user listings. It would seem to be a fairly obvious thing to want to do, especially for social network sites.