Agree on basically all of these, my "Top wants" on cards:
* Ability to "not use" a card in a deck (most games not wanting the 2 jokers in the standard deck being a good example... another good example is card games that use a "sub-set" of the regular deck, like many trick taking games.. Euchre, Pinocle, Sheepshead). Although I like the idea of "quantity" as well given above, then you can set up decks that have multiples of some cards without having to reupload, like "Uno". Based on this feature, would be nice to be able to 'store' card configurations to use later on decks... ie "Poker" deck, "Euchre" deck, etc).
* The "discard" pile issue, although, I would just expand the concept out to be any number of custom "Deck piles". Then you could have options to move a card (or group of cards) to a "pile", either all face up or all face down, and either putting them on top or on the bottom of the pile.
* Option to "cut" a deck.... Yeah, "digital" shuffling really gets rid of the reason why people cut the deck before a deal (cheating during the shuffle), but, would still be nice for "realism".
* "Auditing" on cards... this is a big one. R20 already has excellent "dice" auditing in the chat space, but, right now, people can do things with cards and you can't really tell if any "cheating" is happening. Would be nice to see all events in the chat window on cards (ie, "Deck 1: Shuffled all cards", "Deck 1: Cut deck", "Deck 1: Dealt 5 cards to every player", "Deck 1: Moved all non-dealt cards to 'Draw Pile'", "Joe R: Drew 1 card from top of 'Draw Pile'", "Joe R: Placed '5 of Diamonds' on top of 'Discard Pile'"... and so on).