I certainly agree that there should be some indication on line for deck lists that show whether the card is foil or not.
I also completely agree that on page displaying the details for a card, it would be a huge improvement to link the inventory and 'in your decks' sections. Often if I'm going to a page for a card, I am trying to figure out if I have enough foil copies for all of my built decks or if I'm still short. Being able to see the details not just from the deck list, but from the card detail pages would be a huge help for how I use the site.
This is a feature that would get me back to being a premium member.