Lately I've been thinking about how cards can let you do all kinds of neat things with RPGs (and Guild of Blades' thing with POD cards is also spurring me on here), and thanks to an idea by my friend Mike (Wirebrain), my Raspberry Heaven game (heart-warming high school role-playing along the lines of anime/manga like Azumanga Daioh and Lucky Star) is turning into a thing that uses playing cards.
Essentially, the retooled version of the game has you use playing cards to decide who gets to narrate each of the four parts (Introduction, Development, Turning-Point, Resolution) of a scene, with the suits, face cards, etc. providing a nudge towards certain moods (e.g., Hearts are happy/warm, Spaces are Weird, etc.). So far so good.
The thing is, thanks to being so thoroughly burned out by Magic, I don't play much of any card games, so I don't have a whole lot to draw inspiration from when it comes to card game type mechanics. I want to make it so that characters have Quirks (Tsundere, Space Cadet, Diligent, etc.) to define themselves, and I'm thinking these should let the players do different things with the cards when they come into play (for good or ill; in some cases you can get an "advantage" for making your character look silly), but I have no idea what, aside from perhaps treating certain cards as wild cards.
What other interesting things could one do with cards?