I don't think there is any metal left that's suitable and cheap enough. Aluminium may not be any cheaper than zinc I I'm not sure of the top of my head).
First of all the toll roads in Illinois dose take the cent. I've done it just to irritate them. As to getting rid of this denomination, this subject has been beaten to death many times on this and other forums and everyone misses the important facts. That is that the government really dosen't care what it cost to produce a cent, nickel, dime, etc. When people say the cost of the metal exceeds the cost of the product, so what. It always has cost more to produce out money than it's worth. Everyone forgets the cost of the building they are made in. The cost of electricity, gas, water, phones for that building. Salaries for the government workers there. Miscellaneous items in that building for computers, paper, printers, desks, chairs, refrigerators, toiler paper, etc. Then there is the cost of shipping the coins all over the country in trucks, trains, boats, planes, helicopters, flying saucers, etc. Just what do you think it cost to fly a USF anyway. Most importantly there will probably be no cash money soon. All transactions will be with a credit or debit card. The only thing that is stopping that from being complete now is there is no way to use a credit card on a gum ball machine.
Didn't the GAO say we'd save like 500 million by switching from the paper dollar to the coin dollar? If they won't do that they likely won't do anything with the cent. I barely use cash now as it is. $30 cash in my pocket will usually last weeks. Most stuff is auto deducted, paid online or paid with a check card (no credit cards either). To some extent & with things like the pay pass thing I see advertised we're moving away from cash for many of out transactions in the US.
It is times like this when i wish I too lived in the wide open west! I assume you are being funny, but in case you are seriously asking, some of the governments out this way charge us to drive on the roads, not all of them, just the good ones that you'd want to drive on. I've lived here for 2 years and I hate them! but I don't see it changing anytime soon.
I think this is the important point. We may get away from currency/coin, but there are still parts of the world where precious metal coins are used. Plastic, or memory on a computer, is so far off for them that coins will be with us for some time. We'll all just end up debating if that Afghan 10 Afghani piece is F-19 or VF-20 (http://www.cointalk.org/showthread.php?p=134989&posted=1#post134989).