Have you ever lost your keys?
It's a frequent occurance in our house, so yersterday John decided to solve this problem. He raided my son's lego box, found some blocks and a base block and with the aid of a small drill and a couple of screws, our keys are now to be safely found attached to this lego block.
I think the idea came from pinterest at some point, but I can't find the link. Simple and it works. I even have a huge set of work keys and just one regular block can hold them all. Genius!