It would be great if we could set up folders for our inventory like we can for decks. As a Johnny, with all the UB sets we've gotten and are going to continue to get, it would be nice to be able to make designated lists based on themes. For instance, being able to set up lists for Final Fantasy based on which game the cards are based off of. And while I'm not personally interested in it, I'm sure Star Trek fans would like to organize their collection based on the series from the franchise the cards will be based on. Even ignoring UB, being able to set up catalogues based on things like Artist, or for things like Final Fantasy Through the Ages or the Godzilla Ikoira cards would also be nice.

For more universal applications, setting up sections for different storage options (Storage box, Portfolio, Trade Binder, etc) would probably be super helpful for people who don't have their collection all in one place. It could also help with simplifying deck brewing by letting us set up catalogues based on card function like Tutors, Mana Rocks, Land Ramp, Utility Lands, Board Wipes, etc.