An example of Arduino Due as an USB host mass storage - #45 by system - Arduino Due - Arduino Forum
How to read input from USB keyboard on Arduino
USB flash drive Pendrive 4GB - with resources for Botland - Robotic Shop
BadUsb Beetle Bad USB Microcontroller ATMEGA32U4 Development Board Virtual Keyboard for Arduino Leonardo R3 DC 5V 16MHz: Amazon.com: Industrial & Scientific
Arduino USB key lets you Login into Windows, Twitter, and Gmail with just a Push of a Button