There would be lots of different types of culture cards: religion (and sect cards, too!), holidays, language (dialect and slang cards, kind of like religion and sect cards.), politics, sub-culture cards (those would be my favourites.), mythos, entertainment tastes, symbols (there would be tons of those!), and so on. This would make anthropology work easy, because you could just go through each others' decks instead of years of studying. No cultural misunderstanding, because it's all in the cards!
Best part is, you could trade the parts you don't want. Take the following example:
Satashi: I have too many culture cards! My deck is too big! -_-
John: *Snickers* X3
Satashi: Huh? Oh, right: your "Innuendo, English: Genital" card... Hmm...
Satashi: I'll trade you my matching holiday set ("Holiday: Girls Day" and "Holiday: Boys Day") for it! ^_^
John: What? I'm an American! I have enough holidays as it is! Besides, I want to trade for Rico's "Day of the Dead" holiday card... Man... I want that holiday... X/
Okay, that didn't work. Sorry.
Also, the entire system would keep fresh because old cards (aspects of culture) would go out and new expansion sets released every generation! Think of the future!
H'!nine (go ahead, try to pronounce that.): I'll trade you my "Accent, Ahnklish: Mars" for your "Lingo, English: Programmer"! *Fluffs out her wings seductively* ^'_'^
Coast: Hhhhh-hhh... Nooooo... We chan't doooo thaaat... We're programmer... Work hard for that lingooooo... It is (how to say)... essssssential.
H'!nine: Awwww! -'_'-
John (much way older): Either of you whipersnappers want to trade your "Day of the Dead" cards?
Coast: Nooooo... It's our... favourite holiday...
H'!nine: I don't even know what that is. 0'_'0
Satashi (also way older): Give up, John-san! You'll never have it!
(This has been another one of my... "Bad Ideas".)