We have one of those key safes at home for our front door key (hidden round the back of the house).

They are not really in any way "secure" though, I'm pretty sure the combination lock can be defeated in a minute or so. Not a (extra) worry for us, as our location is remote enough that putting a brick through a ground floor window would be equally as stealthy as opening the key safe.
_________________________
Remind me to change my signature to something more interesting someday