Ooh, sounds like fun, so I'll bite.
My software allows me to set up general categories, and then specific items off of that category. Easy and yet powerful at the same time.
With that in mind, I have a category for:
* Income
* Reserves or Savings
* Bills
* Food
* Car
And.. that's it I think! Short and simple, but that's the way I like it. Of course, off of each categories contain its own short list of individual items, but they should be obvious enough that I don't need to list them.