Are you still leaving a key under the doormat or flowerpot? Shame on you!  The fake rock? So last century.  Here's a great solution: The Sprinkler Hide-A-Key.  It's realistic, unexpected, and only $4.99 from ThinkGeek.com.  While you're there, pick up a few other neat gadgets and toys, and get free shipping on orders over $75 with promo code SHINY.