Arduino compatible boards with a USB stick form factor
...which mean they should end with a USB male type A connector:
CJMCU-Beetle Leonardo USB ATMEGA32U4 Development Board for Arduino - Free Shipping - DealExtreme
CJMCU-Beetle USB ATMEGA32U4 Mini Development Board For Arduino Sale - Banggood.com
Digispark USB Development Board - Digistump
PicoDuino Attiny85 arduino & RGB led from bobricius on Tindie
WINXI - arduino ZERO Pro M0 stick AtSamD21E18 from bobricius on Tindie
PicoDuino AtTiny85, RGB LED, 3+1 Buttons (HID) from bobricius on Tindie
