If you are looking for something unique in a knife, check out the SOG Key Knife. It looks like a key, just thicker, because inside of that fake key lays a knife. You can get a plain blade or a Key Knife with a nail file if that is something you use a lot.
This knife in disguise will cost you about $10-$11(USD). Don’t worry, the knife locks in place in the open position too, so you shouldn’t lose any fingers because it slipped out of place. It even comes with a limited warranty for life.
You can get it from Amazon.