MIDI Keyboards & controllers connecting via USB (without audio i/o)
Amazon.com: NiceTQ USB2.0 Cable Cord for M-Audio Keystation 61ES 61-Key USB MIDI Keyboard Controller : Electronics
M-Audio Keystation 61 III 61-Key USB MIDI Keyboard Controller MK3 + Headphones - Walmart.com
M-Audio Keystation 61 MK3 - Semi Weighted 61 Key USB MIDI Keyboard Controller with Assignable Controls, Pitch and Mod Wheels, and Software Included : Everything Else