We include one of these with every PC HMI, and keep some with us. Rii 2.4G Mini Wireless Keyboard with Touchpad Mouse,Lightweight Portable Wireless Keyboard Controller with USB Receiver Remote Control for Windows/ Mac/ Android/ PC/Tablets/ TV/Xbox/ PS3. X1-Black . https://smile.amazon.com/dp/B00I5SW8MC/ref=cm_sw_r_cp_api_glt_fabc_7ZQ7G64FCPK6D52AC43Z

These have all worked for me without issue on the C1:

https://www.adafruit.com/products/1475

http://www.amazon.com/gp/aw/d/B00009MJKC

http://www.amazon.com/gp/aw/d/B003MTTJOY

http://www.amazon.com/gp/aw/d/B00I5SW8MC

Edit: Specified which Odroid iteration.

I just use a keyboard/trackpad combo like this one. I'd recommend one with a backlit keyboard. https://www.amazon.com/dp/B00I5SW8MC

Non-mobile:

• http://www.amazon.com/dp/B00009MJKC
• http://www.amazon.com/dp/B003MTTJOY
• http://www.amazon.com/dp/B00I5SW8MC

^{That's why I'm here, I don't judge you. PM /u/xl0 if I'm causing any trouble. WUT?}