My Nintendo Registration Gifts so far:
Gift - Requirement
Zelda Collector's Edition Disc (GCN) - Register two of four select games (Mario Party 5, Mario Kart: Double Dash, Avalanche 1080 and Mario and Luigi: SuperStar Saga).
Metriod Prime 2: Echos demo disc (GCN) - Register a total of five items.
Three Month trial subscription to the new Nintendo Power - Register any three items.
Pokémon themed skin for GameCube - Register Pokémon XD.
Pink Kirby Stylus (original DS) - Register Kirby: Canvas Curse.
Three month extended warranty for Wii - Register Wii.
Chance to win GBA game - Register GBA, GBASP or Game Boy micro.
Chance to win DS game - Register DS or DSLite.
Chance to win GCN game - Register Nintendo GameCube.
Custom Robo print - Register Custom Robo (CA only).
Nintendogs - Unknown?
I think that's it... I'm sure someone will correct me if I'm wrong.
Current NoA Promotions:
https://my.nintendo.com/consumer/opr_promos.jsp