Well, soon we'll be seeing new dollar coins - with different presidents on them every three months. The dollar coin would be much cheaper than the dollar bill if it were to replace it because coins last longer than bills. But so far, the public has had little interest in the dollar coins as actual viable currency.
With the popularity of the state quarters program, I think "powers that be" are hoping that changing up the dollar coin every few months will promote interest. I am sure it will, but only to a limited extent. People just don't see them as much and changing presidents is less interesting than changing states - the public identifies with the states, calling at least one of them their own, and sort of had a say in the design of their own state's quarter.
But anyway, I like coins and do a nominal bit of collecting. Anyone ever notice how silver coins have such a beautiful ring to them when they clink together? It is nothing like modern coins. Silver coins are softer, too, to the touch (and in color) - more aesthetically appealing - but also less durable and more expensive, which is why silver is not practical for modern common coinage.
The U.S. mint, in effort to promote its dollar coin campaign, is offering some free stuff - particularly to educators and retailers. If you are a teacher you can get free posters, bookmarks, coin cards, etc. and don't need to pay even shipping, and you can order whole class sets. Free Dollar Coin Stuff - Enjoy.