ABUS has developed a gravity-based skewer lock solution that looks interesting.

The Nutfix system is comprised of security nuts that allow your wheels or seatpost to be locked in place, helping to avoid the most common threat of bike theft. The sleek mechanism only allows the protective cover to be lifted and the nut inside to be accessed when the bike is on its side. The bike locking skewers and locking seatpost makes for a perfect solution to the often neglected security of the seat and wheels.
Even with knowledge of the special functionality of the Nutfix system, would-be bike thieves
would be unable to turn the bicycle on it’s side with when it’s securely locked to the rack.
Available in quick release pair, solid axle and seatpost collar in a variety of sizes and colors (red, black and silver)
MSRP & Sizes:
● Nutfix-Skewer Set -$69.99
● Nutfix Single Skewer (Front or Rear): $34.99
● Nutfix for Solid Axle (one axle): $34.99, available in 3/8”, M9 and M10 diameter
● Nutfix w/ seatpost collar, $44.99, available in 28.6, 30.0 31.8 and 34.9 diameter versions

: Get all the details at Abus.com