ya i wouldn't count animal crossing cards for the same reasons Flee mentioned, but Amiibos/skylanders/disney infinity are all digital devices that interact with the system remotely.
edit: i should note i don't play any of those 3 things nor do i plan on it, i just feel like they should count as hardware.
Animal Crossing cards interact with the system in just as much of a way as the Amiibos/Skylanders/Infinity. We already have the e-Reader games in there...
* bickman2k waits for Tynstar.
at first I was about to question what I said about the animal crossing memory cards because that contradicts my point about "skylanders/amiibos are memory cards so yes to adding them!". I think I meant to say that I wouldn't count animal crossing cards for their own entries because they were never released stand-alone to my knowledge, they only came packaged with the Animal Crossing game itself, so they should be extra media for that. I'm all for any stand-alone memory cards getting their own hardware entry though.
so what I mean to say is:
1: yes to all accessories in the hardware DB that connect to or augment the game/system in a meaningful way. that can be either digitally (Skylanders/Disney Infinity/Amiibo/all memory cards, etc.) or physically (3DS 2nd joystick add-on, PS3 trigger extensions, or anything else along those lines).
2: if the hardware was never released standalone and came bundled with a game or system only, then it should be extra media for that existing entry. this includes animal crossing memory cards.
3: no merchandise. no magazines, no strategy guides, nothing that isn't an interactive accessory (or controller, system, etc.) should be in the hardware database. if anything else is desired it should eventually have it's own place, or sub-place, in the database(s).