You can always count on Vigilant Gear to carry the most interesting E&E/urban survival gear. Their latest addition is the TIHK or Tiny Inconspicuous Handcuff Key.
TIHK is a very compact, non-ferrous, handcuff key with a built in clip that makes it easy to carry in a number of ways including on your rear belt loop where it is accessible in the event that you are cuffed behind your back. The TIHK was designed as a discreet, EDC handcuff key for the purposes of evading unlawful arrest such as those traveling in hostile countries or to aid in escape from home invasions.
Check out TIHK at Vigilant Gear.