Lets see mine would probably be my starfox super weekend cart with high score card that came with it when ordered through nintendo power.
other items that don't really have a rarity rating that I would consider fairly rare would be all my blockbuster world game championship swag (bag, shirt, game promo items, hats and so on) from when I went to the national competition after winning my state's competition. A nintendo store display that lists all the things they won't put in their games (like blood, sex, etc.), this was from the mortal kombat era when nintendo was trying to keep a clean image. A sega genesis Street Fighter 2 Championship banner promoting the game coming out on genesis.