[zarlor]

There are two main methods of categorization from a visual perspective. There is the Categories (and you can make Sub-Categories as well, as you've noticed, but they are not as visibly sub-categorized as I personally would like those to be) and the other way you can use concurrently with that is the Containing Topic method and show things as Nested Hierarchies. So it's two ways you can use to show data. That's just for visual representation, though.

Are you running into the issue of finding something from a list or are we talking about finding something from auto-linking? If the latter then the only way I can think of is to make sure you distinguish your categories with meaningful icons. Maybe use the "Magi Items" magic wand icon for spells, for example, and a Flag for Feats or what have you. Then you just have to remember your icon structures to quickly determine if the name you looking at is the Spell version of something or the Feat or Skill or whatever it is among things that have the same name.