This source isn't a primary source site itself, but has links (22 at time of posting) to sites that help students analyse primary documents. Might be useful.
This site looks like an excellent collection of sources, lectures, images and heaps of other stuff on all aspects of American history. You can even ask a historian a question about US history. How cool!
Does anyone else use Twitter with their classes? I use #historystudent with my senior history students. Please feel free to bring your students onto the feed. DM me on MisterHistory@twitter.com if you'd like to organise collaboration.
"African American history stretches far beyond the confines of one month and the narrative litany of a handful of cultural heroes. Maybe you want to go beyond Martin Luther King, Jr., Frederick Douglass, and Jackie Robinson. What stories can you uncover beyond the headlining stories textbooks provide?"