They say that "idle hands are the Devil's playthings" (and similar), and a court case about paying a bill in pennies proves it.[1] This Texas case is somewhat amusing as a man decides to pay a lawyer in pennies because he "had no respect 'in any shape, form or fashion'" for him. Unfortunately both the trial judge and the appellate court sided with the lawyer, saying that while the man is not guilty of contempt, he followed the letter of the judge's instructions after all, he is liable for the time and cost to convert the pennies into a cashier's check. I personally hope that he does appeal this again, and that he (the person who paid in pennies) wins the case, because if this stands, pennies are no longer legal tender "for all debts public and private," but only for those debts public or private where the debtee chooses to accept them.
[1] Donald, Mark. "Paid in Pennies, Lawyer Takes Fee Fight to Court" Law.com 2005-07-05. http://www.law.com/jsp/article.jsp?id=1120208723965