I would love to be able to filter a deck list for cards I don't have, then be able to use the print decklist based on that filter. That way, when making a new deck (especially EDH, where I can be missing 37 unique cards) I can just paste that list into TCGplayer, order and be done with it. So, a filter or "export missing" or anything like that would be very handy.

Thanks for all your hard work on this site, it's amazingly helpful to all of us!