Yale University has adopted an open access policy for digitized images from its museums, archives, and libraries. Yale has also launched the Discover Yale Digital Commons, which has over 250,000 images.
Here's an excerpt from the announcement:
The goal of the new policy is to make high quality digital images of Yale's vast cultural heritage collections in the public domain openly and freely available.
As works in these collections become digitized, the museums and libraries will make those images that are in the public domain freely accessible. In a departure from established convention, no license will be required for the transmission of the images and no limitations will be imposed on their use. The result is that scholars, artists, students, and citizens the world over will be able to use these collections for study, publication, teaching and inspiration.