I'd eventually like users to be able to have customizable lists that maybe they can toggle to have it count towards their game count or not. That way, they can separate items like swag, wish lists, sell lists, dupes, and digital titles. Or a list just for items that you loaned to a friend, etc.
Hopefully one day!
This is a feature that I've been patiently waiting for as well. It was on Matt's original to do list, but seems to have fallen off of the radar. No complaints though, since I love what the site currently provides. I don't have anything else listed in my current collection except physical and I would love to have a list of my digital games, but I don't want to 'bump' the numbers on that list. I also don't want to manage multiple accounts here, although I consider doing that from time to time.
For me, instead of Collection, Wish List, and sell list, I would do something like Hardware as one list, accessories, physical collection, digital collection, then maybe wish list. I don't even use the sell list (and my wish list is a whopping five items deep).
That's just my two cents.