Jonathan attended FOSDEM 2012 event with his custom made name badge and shared some details of it. This is simple and straight forward design based on MSP430F5171 16-bit microcontroller that controls 5×8 LEDs where the name is scrolled.
LEDs are connected in rows and columns, so five and eight pins of MCU are occupied. No limiting resistors or any transistors are used as leds are driven dynamically. Badge is powered with 3V lithium coin cell. PCB is double side and home made. Jonathan used toner transfer method for this and results are great. 6 mil tracks look really great. After tryout he suggests to add more LEDs to get better resolution as 5×8 is pretty hard to read. Anyway this is great way to stand out in a crowd.