Behind those books - a secret door!
I don't know if it was Nancy Drew or the board game Clue or Scooby Doo, but at some point I imprinted on secret doors. Particularly secret doors hidden behind bookshelves. Pull a book and - surprise! - the shelf swings open, revealing a hidden room (or secret passage, or steps going down, or something grisly).
Nowadays homeowners can get bookshelf-disguising doors of their own. There are multiple retail versions and at least one custom designer. What the bookshelves hide varies, from saferooms to unsightly laundry rooms to rooms that become wine cellars. Sadly, the products seem too major to try to install in a rental, unless you have a landlord with a sense of intrigue.
One Australian with DIY skills built the shelves above, which, in the spirit of hidden doors, open when you pull on a Sherlock Holmes book. While his shelves conceal nothing more than a broom closet, with his talents I bet he could construct a secret passageway -- maybe to a conservatory.
To see one bookshelf do its thing, check out the video after the jump.
Hidden door in action at a builder's expo: