Adafruit has published some new Business card-sized references for Arduino and basic electronics. Adobe Illustrator format files are available for download on their github.com repository.
Adobe Illustrator format. These are sized for Overnight Prints‘ standard business card template; full color, double-sided…rounded corners are optional but add a touch of class (and won’t cut off any information). Creative Commons license, feel free to print your own, remix and share!
Electronics & Arduino Reference Cards – [Link]