[martin]

Something like this is required as part of the recently enacted CARD act (in the US):

"Credit card issuers must disclose to cardholders the consequences of making only minimum payments each month, namely how long it would take to pay off the entire balance if users only made the minimum monthly payment. Issuers must also provide information on how much users must pay each month if they want to pay off their balances in 36 months, including the amount of interest." (http://www.creditcards.com/credit-card-news/help/what-the-ne...)