It's not uncommon to keep a spare set of keys or a few extra bucks in a kitchen drawer. Since it's not uncommon, it's also a place sneaky guests might check to pilfer. If you want to keep your valuables a bit more hidden, check out this guide for building a hidden compartment in your drawer.
The Instructables guide below shows how to cut a small space into the bottom of one of your drawers. You obviously wouldn't be able to keep stacks of cash under there, but a spare key would be safely out of sight. It won't be invisible if someone empties the drawer, mind you (though it's possible to improve upon this design), but it should keep precious items away from prying eyes.
Hidden Drawer Compartment | Instructables