Open Source
There are tools and then there are tools. Resource that are free for all (for now). The mind boggles. Some cases in point:
The Wikimedia movement - just a few of:
The Public Domain Review
- Also brings us: The Public Domain Image Archive
The Warburg Institue
- As they say "The Warburg Institute is dedicated to the study of global cultural history and the role of images in society. It examines the movement of culture across barriers - of time, space and discipline - to inspire, inform and connect."