- Allow monthly payments, instead of only weekly: most people receive money monthly so their economy math is based on monthly periods.
- The company giving the biggest amount of money is giving $1095... you should try to involve Mozilla and other big non-profits to donate, basically because giving monthly money to open-source (non-employees) devs is one of the boldest statements they can make in favor of open-source.
- Create spontaneous requests, for example if someone is giving 10 dollars to some folk the app could pop up and ask if they want to give her/him a one-time gift of $20, and ask again once the next month (just remember to also show a checkbox to disable those notifications). The people is full of greed based on impulsive behavior, why not let generosity also be impulsive?