I pug a lot, and I like to add people to my friends list for a variety of reasons. They could suck, but have a nice attitude, they might be competent but not very nice, they might be horrible in all respects, etc.

I want the friends list to be able to be separated into user defined subcategories.

I might, for example, invite the competent mean guy into a difficult raid, but not a casual quest. And the reverse for the funny noob. Being able to organize the people I work with would make that easier.