• one person may have borrowed $1M many years ago and have just finished paying it back;
• one person may have just opened an account with no deposited money, nor borrowed money.
• one person may have borrowed 100 times $1,000 and paid each time back.

Same balance, but very different levels of value and risk contributed.

On how to improve the account balance, there is a lot we can learn from exchanges not based on bank money, such as time banks, bartering networks or gift circles.

The San Francisco Time Bank for instance shows the balance, but also the hours received and given:

The sharing Web site Neighborhood goods accounts for the money you saved your friends by allowing to borrow your goods (and, I believe, until recently  the money your friends saved you).

Finally, Martien van Steenbergen proposes a very elegant measure of trust: the number of times you’ve changed the sign of your balance i.e. the number of times your balance went through zero.