The (expensive) Yubikey Neo Nano already supports U2F in the 'micro key' form-factor: http://www.amazon.com/Yubico-Y-110-YubiKey-NEO-n/dp/B00O8ST7MM/ http://ww

The (expensive) Yubikey Neo Nano already supports U2F in the 'micro key' form-factor: http://www.amazon.com/Yubico-Y-110-YubiKey-NEO-n/dp/B00O8ST7MM/ http://www.amazon.com/Yubico-Y-110-YubiKey-NEO-n/dp/B00O8ST7... Hopefully they'll come out with a cheap U2F only nano-key soon.