Using rasp pi and universal coinslot to monetize your wifi connection. At first I thought this is just for home projects but it turns out this can be a good business opportunity
Raspberry Pi Piggy Bank with Coin Sorter - Alex Strandberg - YouTube
Amazon.com: Multi Coin Acceptor, 6 Kinds of Different Coins Selector Acceptor, High Accuracy, Anti-Phishing, Anti-Mixed Coin, for Vending Machines, Game Machine, etc : Industrial & Scientific
jinyuetek raspberry pi arcade coin slot| Alibaba.com
Coin acceptor: read GPIO - Raspberry Pi Forums
Programmable Coin Acceptor - RobotShop
Amazon.com: Coin Acceptor, CPU Multi Coins Acceptor Selector with LED Indicator, Game Coin Slot Acceptor Coin Acceptor for Arcade Game Vending Machine : Industrial & Scientific