I have two ideas but I'll start with this one.
Flex-View Poker Cards
Playing cards with three different types of indices, specifically designed for different types of poker.
All faces custom, based on standard deck faces (see below). Traditionally cut with Tally-Ho stock & Linoid finish.
Colors will be deep crimson and black, including court cards. Backs will be black on red, red on black.
I thought of these cards as a possible improvement to the PokerPeek design that's common with Texas Hold 'Em players - I wanted a card that would be well-suited for both Hold 'Em and other games where the cards are held fanned in your hand. I'm no artist, so I'll try describing my vision for them. In the left corners, a standard index. In the right corners, a "peek" index, smaller. Dead center and slightly elongated, pips/court designs, borderless with a white background. On the left side of this, an elongated jumbo index done vertically. (Same index on the left when card is inverted.) The nine and six will have a line under the number to indicate orientation of the number and prevent confusion similar to what happened when PokerPeek was introduced at the 2007 WSOP. Peek index corners will be kept as empty as possible aside from that index, to reduce chances of an opponent seeing a card flash. Card backs will be a simple, refined, white-bordered pattern, without a great deal of detail to reduce the possibility of visible markings - perhaps a simple medium-to-large two-way geometric pattern. Not a great deal of flash, probably not a great deal of appeal to the magic/cardistry folks, but poker players might welcome them with open arms.
There are possible ways to fiddle with the jumbo indices and the pips/courts, even possibly making them with a one-way face, but the basic concepts of a standard index left corner and a peek index right corner are the main design ideas here. They'll function as well at Hold 'Em as they would in a "squeezers" type game with players holding card hands.
My other idea was something simple, though short on details right now. While staring at the back of the Guardians I got the though of creating a black deck with a thin white border on the card backs and fronts. Done right it would look really elegant and wouldn't suffer the edge damage of ordinary black cards. Or, and this is real pie-in-the-sky thinking, what about a borderless black deck with a black card stock? Edge damage would be a thing of the past, though printing would have to be radically different, probably in the form of some kind of applique ink akin to silkscreen. Imagine a silkscreened deck of cards? And the work it would take to make it? It would practically require retooling the card printing process - but it would be pretty cool to have black cards that don't need to be markered on the edges to retain that cool, all-black look.