You could add option for monthly payment reminder regarding outstanding amount .
I have been tired of asking for money to people who owe me. If they registered on Splitwise using their email/phone number, I would like an ability to automatically send reminders through Splitwise every month so they don't forget. It's been years since some people owe me money and it's uncomfortable to ask them money every once in a while.
I think its custom reminder like i will only add my self to me to remind that pay this insurance payment on this day.
I love the app. it would be a cool feature if you could click on a button on each friend to send them a settle request (app notification and/or email). For example you click on your friend "Mad Max" and then you click on a button called "send payment reminder" and then an email gets sent to your friend asking him if he can make a bank transfer etc. That would be helpful for me since I split utilities on your app