My dad bought me this tiny harmonica on holiday (my family know I collect tiny things now). This harmonica keychain isn't really much more than a simple novelty. It can play 8 very shrill notes and I doubt anyone would consider it to be a real musical instrument. But it's tiny, it makes a noise, so here it is.
Another mini childhood game on a keychain from Basic Fun / MB / Hasbro. It's a little bigger than the Battleship one so the counters can be a playable size.
The whole thing folds neatly away into itself when not in use. Click here to see what this looks like.