Keys

Keys are the coolest thing ever. The "key and lock" system of technology (from ancient to modern) is really, really great.

Keys open things that "require security for some reason". Doors, chests, lockboxes, fucken trapdoors... dozens of lockable possibilities. But the best concept is what's inside. Endless potential. I'm totally going to "lock something away" right now, purely for the novelty value of it all.

Editor's Note: wearing a key as a pendant around your neck is pretty awesome, too.

Attics are mysterious and cool

I really love "forgotten places" in houses; a very common "forgotten place" is an attic -- a room in a house roof which you might not even know exists. But what's even cooler is the thought of discovering something long forgotten, valuable or bizarre hidden in one!

Imagine living in a house for a while, discovering you have an attic, and then "venturing" up there and discovering something that the previous owner forgot up there, something with a "story of its own". Like a really old child's doll, or a box full of love letters from a century ago, or a "lockbox". Ohhh man, so cool.