CardStick Ruler Decals
Gadgets that manage to fit into our lives without filling our pockets with more clutter are great. For example the True Utility Key Emergency Tool that piggy backs on top of an existing key or the CardStick (pictured above) which allows you to affix a ruler on to your ID or credit cards.
Not exactly earth shattering, but a simple an smart idea. You get a set of 3 for $3.99 here.