While I would prefer a device and app that cures the back pain caused by my poor posture, I suppose a combo that encourages me to improve my posture to preclude back pain is...well...a distant second since it basically requires me to do all the work, but OK. As with most areas of my life, I'll take what I can get.
LUMOback promotes healthy posterior chains with its synergistic sensor and mobile application, currently available for: iPhones 4s and 5; iPads 3, 4, and mini; and iPod 5. The LUMOback sensor, worn like a belt at the low back area, gently vibrates when proper spinal extension and alignment start to crumble, reminding the sloucher to sit or stand up straight. Similar to a nun with a ruler, but less traumatic and likely to require post-childhood therapy sessions.
LUMOback sensors also connect wirelessly to iThings to track and record all movement data. LUMO, a personal avatar/stick figure doppelganger, mirrors daily activities so you can see what your posture looks like at any given moment, and also learn what it feels like to be two-dimensional with the head-body proportions of Keira Knightley.
Two sizes of LUMOback sensors are available: S/M, for waists 28" to 38"; and L/XL for girths of 33" to 50".