We met an entrepreneur at a business course who was establishing a business operating coin counting machines. The customer poured coins into a slot and receive a receipt for that amount redeemable at the local shopping centre.
He had a solution for the hardware, but needed a way to monitor the machines and track income.
We wrote a server based solution which received commands from each machine through the GPS network and stored transaction and status information in a database.
An admin system written in Django presented the information for monthly reconciliations and error reporting.