I architected a solution for hotel management, which allowed an IPTV broadcaster to provide hotels with a solution for guest management, billing and integrated this with STBs in the hotel.
This system had several components: the STB application, that allowed guests to check their current balance, watch TV, Video on Demand content, etc; the receptionist portal, which allowed the hotel receptionist to check in/out guests, add items to their bill, etc; the management portal, which allowed the broadcaster to manage the hotels, send out invoices of services rendered, handle languages and (limited) customization of the STB portal the guests saw, etc; and an API to integrate the billing system of the hotel with the backend components of the solution.
This was a quite challenging system to build, due to the fact that it was an end-to-end solution that would be handled by people with different skill-sets and motivations.
Most of the backend was built by me (in C++/Lua), while I managed the rest of the implementation of the project.