I often borrow cards from a friend, or lend some of mine out for a friend to use in a deck. It's not a trade since I still own the card if I lend it out. It would be great if there was a way to track which cards you've lent out and to whom, and if you have any borrowed cards, who the owner is.

One way to possibly implement this would be to set up a "trade" (maybe with yourself, although ideally with someone else), and "ship" the cards (taking them out of your inventory), and then an option when if you cancel a trade, it asks if you if you want to add those cards back in.