It would be nice if we could easily add cards that don't exist in the database to a deck. There is a workaround where you can use the import feature and just type in the card you want to add into that list. It would be nice if we had a direct workaround.
Secondly, it would be nice if cards unknown would at least display their name when you draw them, currently it just shows a blank grey card. Just the card name would be good enough.
Minor features, but it would let us test decks right when new set is out or when new cards are spoiled.