Seit Kurzem ist das Public Domain Image Archive (PDIA) online (via publicdomainreview.org):
“After the hundreds (thousands?) of hours trawling through online image collections since the PDR’s inception, we’ve decided it was time to create one of our own! We are really excited to share with you the launch of our new sister-project, the Public Domain Image Archive (PDIA), a curated collection of more than 10,000 out-of-copyright historical images, free for all to explore and reuse.”