Found a neat article showcasing the worst items in video games. I have to agree with most there. Except the single banana in Mario Kart... you can hold it behind you to ward off an incoming red or green shell, throw it in front of you, or hold it behind you as you cut off somebody, making them spin out as your back clips them... and... when they are laid, the computer karts always seem to fall for them when placed on a corner.
http://www.ugo.com/games/useless-video-game-items