I'll support Nick's call for penny elimination below. Here in Singapore we're transitioning through the elimination of the 5-cent coin. (The penny, depicted at top right, was abolished well before my time.) Merchants will accept the 5-cent coin, but prices for lots of things are in 10-cent increments and it's slowly receding from circulation. At current exchange rates, the Singaporean dollar is worth 77 US cents, so we're basically moving into a system where the smallest coin is worth 7.7 US cents. We're enjoying the benefit of not fiddling around with insignificant coins, with no obvious drawbacks.
One of the nice things about the Singaporean system is that it's pretty well suited for transitioning through nickel elimination. Any value difference between any quantity our remaining existent coins can be bridged by some number of ten-cent coins. This works fine in the US system as far as penny elimination is concerned, because you can bridge any gap with some number of nickels. But in the future we're going to have trouble getting rid of the nickel, there's going to be trouble because if something costs 20 cents and you've got a quarter, there'll be no way to make change. Going straight decimal instead of messing with quarters would've had its advantages.