When I've needed to do this, I've used a spreadsheet (with some sophisticated conditionals to get a net "you owe" matrix for each person in the group based on a

When I've needed to do this, I've used a spreadsheet (with some sophisticated conditionals to get a net "you owe" matrix for each person in the group based on a list of shared expenses paid for by different people. In other words, it isn't a startup IMHO - certainly not something I would pay money for. I should put the spreadsheet on Google Docs Templates I guess.