LIBUSB is a Ruby binding that gives Ruby programmers access to arbitrary USB devices

ruby-usb is a libusb binding library for Ruby.

Provides a convenient wrapper around libusb to read credit cards with a Magtek Credit Card Reader.

BlinkStick provides a ruby interface to an Agile Innovative BlinkStick via libusb.

A little library for a little wire. Providing a pure ruby interface (via the nonpure libusb gem) to littlewire.cc's wonderful gadget. littlewire.rb provides general purpose digital IO, pulse width modulation analog outputs, analog inputs, SPI, I2C, WS2812b, One Wire, and rough servo control via a friendly interface which responds both to familiar Wiring/Arduino style methods and a more concise ruby alternative. LittleWire can be installed on to Digispark devices, offering a very extensive firmata-style option for digispark users.

RibUSB is a Ruby extension that makes USB devices accessible from Ruby via the libusb library (API version >=1.0).