This is a primary source document . . . in Spanish! It is purported to be (as I'm no hispanohablante) a letter from 1570 that "describes the settlement at Ajacàn and requests that Juan de Hinistrosa, the Royal Treasurer of Cuba, send a ship of grain to sustain the settlement." This would be great for Spanish class, obviously, and then maybe for world history after the other students translate it. :-)

The American Memory collection is such a treasure trove, including this old photograph of Sioux City (as well as many other Iowa towns). This would be really useful in a unit about local history or even for younger students, talking about communities and maps. Students would find it interesting to match up today's view of the city with this one.

This site has a lot of primary source documents about Wisconsin history, but which certainly pertain to the rest of the Midwest, too. The one linked to is of an 1838 newspaper article about the first careful investigation of effigy mounds undertaken in Wisconsin. Certainly this could be useful when studying Native American history, state history, or geography.

Here's an interesting little tidbit, a personal letter and then newspaper column (fully transcribed) about fighting the Spanish Flu of 1918. Could be useful in health class?

This college textbook publisher site has primary sources on several different events in Europe - see http://college.cengage.com/history/west/resources/students/primary/index.html for an index. The text is here, no imagery, but for high school teachers, there is a lot of good information here.

Next time you are in Chicago, go to the Oriental Museum at the University of Chicago - incredible! But until then, check out their website for images of artifacts, maps, video interviews with archaeologists, and lesson plans.

Here is a collection of paintings by Crockett Johnson (1906-1975) which are dubbed "mathematical paintings" and could be studied in both art and math. The one linked is Archimedes Transversal, but 80 total are included in this online collection.

David Kinnison was the longest-lived participant of the Boston Tea Party, living to be 115 years old which is old in any decade! Here is text of an interview Kinnison did with John Lossing, author of The Pictorial Field-book of the Revolution, in 1850.

The University of Iowa Archives have put online scans of Civil War diaries, including soldiers held at Andersonville Prison, with full transcriptions to make sense of that 1800s penmanship.

This website is a veritable prize for teaching the Civil War. There are full page scans of every weekly issue of Harper's Weekly during the Civil War. Beautiful line art and verbose writing style included for free. The site has Google ads, but no pop-ups at least, and the content is valuable enough to be worth wading through those. The site is easily navigated, so that isn't difficult. Great for writing Civil War DBQs.