Library of Congress source images at popartmachine.com

I just wanted to mention, if you find an image at LoC P&P that you'd like to upload, but all that seems to be available is a thumbnail GIF, you can usually find the source TIFF image by searching the LoC reproduction number at Pop Art. Once you've found the pic, you can also click on the small JPEG and make it a bit bigger. If you're planning to crop a face out of a large image (example), you'll probably want to download the Source Image TIFF and transform it into a JPEG.