Not much for the 9-12 grades. Could be fun for lower grades
Overall I think this site is directed for the lower grades and not toward the high school students. Given the site is from the US Mint I had hoped for information or lessons that could be used in Economics courses and possibly teach about the history of money in the country (gold standard, history of printed money in the US, and/or Secret Service and anti-counterfeiting)
The games are not anything that would hold the attention of a high school student and the graphics would disconnect before they gave it a shot.
How I Use It
http://www.usmint.gov/kids/teachers/lessonPlans/viewLP.cfm?id=197 This was the only lesson that I could find that would be helpful for high school students. The lesson focuses on Westward Expansion after the Louisiana Purchase. It focuses on the use of the new nickels which to me seems like they are trying to generate interest in the coins and collecting. The lesson is well designed but rather long as it is intended to take multiple days to complete. The first 2 days are data collection with the second 2 days being devoted to essay prep and writing.
A nice part of all their lessons is that it shows a connection to the common core and the national standards.
As a hobby site this would be good for giving students information about the coins the faces and the imagery.