Assuming you reached Gold or Platinum status this year, at least. Lots and lots to choose from.
Platinum: Mario themed playing cards or a set of posters featuring Luigi's Mansion: Dark Moon, Kid Icarus and Zelda: Skyward Sword.
But wait, there's more!
If none of these things appeal to you then you can pick one virtual download from the following! These are available to you regardless of which status you reached (with a minimum of Gold, of course):
Super Mario Kart (3DS)
Metroid II: Return of Samus (presumably 3DS)
Mario vs. Donkey Kong (3DS (this game is awful do not get it))
Zelda: Majora's Mask (Wii)
I think I'm going to get the playing cards. The posters... seem interesting but they're just not unique enough. Plus I don't hang posters on my walls because I'm not 7 any longer--not that I would hang collectible posters to begin with.
Redeem or check for more information here: https://club.nintendo.com/elite-status-gifts.do