The U.S. Mint, founded in 1792, creates all U.S. coins; and guards the nation's gold and silver, as well as the U.S. Bullion Depository.
The Mint site offers a wealth of educational resources, not just within the "Kids and Teachers" section. Some are difficult to locate, but the following links should prove helpful.
If you are looking for information on the mint itself, consider the timeline, which covers 1776 through 2006; an overview of the Mint's various roles; information on coin production; or the available articles on coinage history.
Maybe you need a primary source? For visuals, try the image library, which offers pictures of circulating and commemorative coins. If you need a document, such as legislation, press releases, or ledgers, the best option is the Mint archives. Uncheck the box for coins, if you would like texts only.
Finally, there is, of course, the aforementioned children's page. Here, you can find animations on world coins, major historical moments, and coin production; current and past coin programs; recommended reading; and the stories of the Mint's five facilities. Specifically for teachers, the section offers a teacher's guide to site resources, suggested projects, and lesson plans.
Need to get out of the classroom, and onto the street? The Mint offers tours of its Philadelphia and Denver facilities. You don't live in those areas, or can't arrange an excursion? The site offers a virtual tour as well.