This is another useful side project. The scenario: In a shared flat of 4 people, everyone buys something here and there which will be used by the whole flat. To make this very fair, people wrote it down at a certain stage and then divided it equally.
I did this with Microsoft Excel. Each one will simply type their goods into the worksheet and Excel automatically tells you who owes whom. It’s even pretty sophisticated: if two people owe each other, it will automatically subtract the two values, and the one who owed more, only pays the difference. If you desperately need this for your flat, email me here: email@example.com