These are actually a couple of sites students asked me about. The 8th graders are doing their 1920's research paper. One thing I love about the WWW is that no matter HOW many hours you spend dredging for pathfinder sites, there's always something else interesting and valuable.
Our Documents is a national history competition based around 100 key documents from the National Archives. The link is to their collection of documents, which are downloadable. You'll also find a 74 page booklet with teaching ideas here. The entire site is a joint project of National History Day, the National Archives and the USA Freedom Corp.
As a Tacoma native (and Seattle's close enough), I found the Seattle General Strike Project fascinating. Washington State has always been a strange mixture of xenophobic conservatives and left-wing radicals. This site documents the Seattle Labor Strike, the first labor action in the country to be declared a general strike.
The multimedia site includes images, video, oral histories and images of actual headlines/documents related to the strike.
The above picture is from the Webster & Stevens Collection, Museum of History and Industry.