The United States' one-cent piece, the penny, has outlived its usefulness as a medium of transaction, and should no longer be minted. Inflation has devalued the penny so greatly that is no longer cost-effective to produce or use.
In the past, the Obama administration has proposed decreasing the value of the materials in the one-cent piece to save money. However, reducing the material cost of the penny does nothing to offset the fact that it costs 1.8 cents in labor alone to mint one penny. (http://www.dailyfinance.com/2012/02/13/a-penny-saved-is-more-than-2-penn...)
Australia stopped minting one- and two-cent coins in 1990. Canada ceased production of their one-cent coin in 2012. Maybe it's time we do the same.