I think gamification of "saving habits" would be very interesting - something to encourage you to save more. But it shouldn't take a lot of time to set-up or be confusing. If it would be automatic, even better.
The set up time is important- it seems to take too long to really get Mint set up to the point where it's useful, and then you still spend a lot of time recategorizing transactions so that you can know where your budgets really stand. I know that's not an easy problem to crack, but something with less detail that can encourage better overall spending/earning/savings trends would be pretty useful.
