Long time user, brand new Premium subscriber here. You've already got my money, but here's a few feature suggestions that would make my day:
* In the edition list view, show the completion status (X/Y cards) of each set, with options for "any printing" and "this printing".
* In edition list view, have lists for the current modern/standard legal card set, as well as the reserved list and banned lists for various formats
* In edition view, have a tool to add of of every missing card to my wishlist.
* Public and private wishlists

Thanks for such a great site!