What is a rare date for a liberty head nickel?

Among standard issues, the 3 most valuable dates are

1885 - values for circulated coins range from $500 to $2300 as of 08/2011

1886 - $220 to $1100

1912S - $150 to $1400

Of course, these are nothing in comparison to the price of a 1913 Liberty Head nickel. Only 5 of these coins are known. They were never authorized by the Mint but aren't considered counterfeits because it's generally thought that they were made surreptitiously by Mint employees using dies that had been prepared in case the new Indian Head design wasn't ready in time. It's almost impossible to put a value on them but as of 08/2011 the most recent price for the finest known specimen was in excess of $5.4 million.