In our office, next to the coffee machine, we have a classical paper tally sheet where people fill in when they had coffee, and someone at the end of the month will count all the marks on the sheet and tell the people what they have to pay.
Problems are: the sheets never show the actual debt the people have, and it's always tedious work to count the marks.
But since we already have some (non-touch) info-monitor hanging in this room that is driven by a Raspberry Pi 2 running Ubuntu, I'm searching for a more interactive solution for coffee billing. What I had in mind is something that can be shown within an internet browser like Firefox, an where people just have to press a button next to their name to add a coffee to their bill, and all "debt levels" shown are always up-to-date.
Also, if possible, there should be something like a maintenance back-end where only certain people can free coffee-drinkers from their debts as soon as they pay them.
I would not want to use some kind of spreadsheet, since it's probably error prone, and not really save top manipulation and wrong use. For the users, it should be as simple as possible, if possible.
Does anyone of you know some program or project that might can be used for such an application? Any hints are highly appreciated! Thank you!