On demand food delivery service where customer can select from restaurant's menu on his phone app and make payment. Restaurant gets notification on his app UI and prepares the order, notifies when order is ready. Nearest delivery guy(to the restaurant) gets notification from restaurant on his mobile app and picks up the order from restaurant and delivers to the customer. Operations manager can oversee whole operation on his web panel(computer)
This is very high level requirement mentioned detailed requirements might have some extra functionality not mentioned here.