This fifty-page PDF from the European Central Bank tells the history of the euro from the early 1990's to release in 2002. It includes pictures of some the currencies it replaced, and a chapter on the design of the euro banknotes.
For high school students and grownups, CNN presents a roundup of news articles about the euro's current crisis.
What fun! These printable euro banknotes come in denominations of 10, 20, 50, 100, 200 and 500 euros. There is even a printable set of coins.
Surfnetkids.com recommends five websites about the Euro.