As featured on HAD: http://hackaday.com/2014/03/13/automatically-accept-membership-fees-or-donations/
A bill acceptor first needed to be trained to accept Japanese yen. The box accepts donations and membership payments (selectable by illuminated buttons). It will then print an appropriate receipt.
There is a real time clock backed up by battery, and basic accounting data is recorded to FLASH memory.
Build log is here: http://diy-scib.org/Project/ths-membership-box
Code and Eagle files: https://github.com/DIYsciBorg/Membership-Box