manekinen developed a small sized (24mm x 85mm) electronics business card. It is based on Atmega88V microcontroller. Device is meant to display text messages, scroll, and do other effects. There are four buttons on board where you can enter text without any other external means.
PCB is double sided where one side contains only LEDs soldered as matrix and on other side there are other electronics which is actually Atmega88V, four buttons, 3V coin battery and circuit to drive LEDs. All is SMD what makes it compact and great looking.