Many Flickr users have chosen to offer their work under a Creative Commons license, and you can browse or search through content under each type of license.

A collective of institutions that have uploaded publicly held photography collections. Images found in Flickr Commons site have “No Known Copyright Restrictions."

You can limit your results to creative commons by selecting "labeled for reuse" under usage rights.

A media file repository making available public domain and freely-licensed educational media content, including images, sounds and videos.

This catalog contains photographs, fine and popular prints and drawings, posters, and architectural and engineering drawings.

A collection of over a thousand images of significant historical interest scanned at high-resolution