It uses NXP LPC8N04, and features nine 0.4 mm slim orange LEDs for the light show and feedback. The MCU itself consumes only 900uA at 8MHz and 200uA at 1MHz. Given that NFC readers provide power continuously, there are many application that could be implemented on the business card. I haven't came up with anything fancy yet, except for hooking up I2C sensors, and using LEDs and time interval that card is held against the NFC reader to change the mode of operation. If you have any ideas, leave the comment below!
I was playing with this design and found the NFC powered stabilization capacitors are recommended to be put on "high-drive" pins. They are 0_3, 0_7, 0_10, 0_11. The are mentioned in the data sheet but called high-source pins therein (confusing). The Users Manual has them identified and called out consistently as high-drive. Don't know if your board layout will accommodate a pin swap 0_1 for 0_3 or 0_7. (10 and 11 you have committed to the break out) You may get longer on times for your LEDs when pulled from the NFC field.