We have friends who stash their keys outside when they're away. The secret hiding location is known to a few friends who may need access to their apartment in their absence. We think this is crazy, but, if you're going to do it, you may want to lock it up. This Slimline Keysafe by GE Security opens upon entering an access code.
It's kind of like the key box built into many residential buildings around the city for the post man. Now, we still recommend just leaving a spare key with a trustworthy neighbor. But we thought this little wall-mount safe could help out our friends.