One of my favorite blogs, Square America, has posted an online show titled African-American Portraits & Snapshots, a collection of 160 photographs taken between 1900 to 1975 (several home movies are also included). It's a rich and varied collection that I hope gets put into book form some day. Note the site takes a few seconds to load and the site curator Nicholas Osborn mentioned he's still tweaking the layout, so things might change in a day or two.