Here's an interesting article regarding currently circulating US coins: http://news.coinupdate.com/the-unusual-state-of-our-circulating-coinage-1114/
Thanks for the article. It's funny how our government works. The coins that produce almost 70% of revenue from seigniorage, are the coins they want to eliminate. Smart.
Yes, I just happened to come across it (it was a link from coinflation.com), and thought it was very interesting. Probably nothing new, but I thought it did a great job to succinctly summarise all six denominations in one article.