A really nice site!
As a collector, I would really like to have a kind of 'checklist' for each set, to easily see what I am missing. The best method I've found is to use the cards database with the 'Edition printed in' filter. However, in the spoiler view all cards display the number zero. Also, this method displays other editions for some cards.
Would it be possible to add an easily accessible list (for each set that one owns) which just displays the total inventory count for each card, and where the missing cards are e.g. grayed out? This list should obviously display the correct editions of the cards in pop-ups.
It would also be nice to have a kind of 'progress bar' somewhere which shows how many cards that are owned of each set.