Meet the vending machine that tweet shames candy bar buyers . Would you think twice about your sweet treat if you knew that an automated dispensary would tell the world about it?Source: YouTube user Computerphile 
A UK-based group of creative crafters called Nottingham Hackspace  has revamped its snack dispensary into a tweeting machine that keeps its members accountable for what they eat. After a successful pledge drive, the group was able to buy the vending machine off eBay. The hackers then enhanced the purchase with Arduino , an open source electronics prototyping platform.
Using Arduino, they've modified the cash payment system with a little reader onto which members tap their cards. The cards have a little RFID (radio-frequency identification) chip that wirelessly transmits who they are and how much money is on their card to the vending machine.
It also communicates with the Nottingham Hackspace server, Holly , who then tweets your candy bar purchase. We're thinking that we'll need to get one of those in our office.