Current solution to manage monetary expenses among friends already exists. Apps like splitwise, GroupMe or Square Cash already provide a very useful tool when doing trips, fairly allocating debts and keeping

Splitwise Share bills and IOUs and make sure everyone gets paid back Screenshots Hunter's comment Splitwise app let you split household bills with your roommates, or even figure out expenses for a group

Splitwise New App To Split Bills & Share Expenses in Real Time Screenshots Hunter's comment What I like about this app an ingenious way to help you calculate the shared expenses among your friends