Here is a nice list of all the methods https://proconnect.intuit.com/community/help-articles/help/depreciation-methods/00/3537 you might bookmark for reference.

There is a drop down for Category (Ctrl+T) and following that is where you can make up your own. Just a warning, be sure to type your special category exactly the same each time. In my example I used Dohickies this is different that just plain ol' Dohicky  or Dohickie. Each of those 3 would be their own category. 

These can be use to present a nice depreciation worksheet with totals for each of the categories. They could be Divisions in the company, or division in types of assets.