You know those neat car remote gizmos that have your car key stuck to the side as a switchblade? Endless fun, simple answer to the standard jingling car keys bit...
But you have more than one key.
Solution? Stick them all on your car remote gizmo! Every necessary key (limit of 5) replicated
by your car manufacturer and placed INSIDE your car remote gizmo!
Would feel the same as a VW's car remote switchblade key combo, but would have a thumb wheel going horizontally across it, which would be used to thumb to the next/previous key, thereby aligning it with the switchblade mechanism to pop it out at the press of a button.
Any licensed Switchblade Keyswapper(R) manufacturer would simply copy your keys with their appropriate proportions to a base that fits the keyblock of approximately the size of modern day cell phones. Minor assembly required and Gablamo! Keep all your keys in an incredibly convienant place.
Patent and worthwhile mspaint drawing pending.