If you use primary source documents in your classroom, the Library of Congress Teacher's Page is a site you should check out. A part of the Teacher's Page is the primary source center. The primary source center walks teachers through the process of locating documents on the Library of Congress' site. The primary source center also provides guides for using various types of primary sources including political cartoons, photographs, and oral histories.
Applications for Education
When I was a just starting out as a history teacher I knew that I should include primary source use in my classroom, but I wasn't quite sure how to go about it. Fortunately, after some stumbling around a colleague gave me some of his primary source-based lessons which gave me a much better handle on how to use them effectively. Hopefully, the Library of Congress Teacher's Page will help new history teachers avoid the stumbling process I went through when I started out as a history teacher.
Here are some related items that may be of interest to you:
Textbooks, Wikipedia, and Primary Source Research
The Avalon Project - Hundreds of Primary Documents
National Archives Our Documents Source Book