there's reddit news outside proggit?! in seriousness, though, reddit's category system is broken because it lacks inheritance. people should be encouraged to provide the most specific leaf categories that apply when submitting articles. viewers may then customize as broadly or eclectically as they wish (ui can do the abstraction, whereas in the database every user has true/false on leaf nodes). auto-discovering categories might be useful. the fail point is still on ui, not performance, imho.