NASA has just joined The Commons at Flickr, bringing the current number of participating institutions to 46. As with all images in The Commons there are no known copyright restrictions, a fact worth noting whether you are a a scholar or creative artist.
The Commons' objectives are:
1. To increase access to publicly-held photography collections, and
2. To provide a way for the general public to contribute information and knowledge. (Then watch what happens when they do!)
To enhance understanding and access to the images in The Commons, members of the public are encouraged to share their perspectives and even expertise by tagging images. But as Flickr notes, "Any Flickr member is able to add tags or comment on these collections. If you're a dork about it, shame on you. This is for the good of humanity, dude!!"
Image: Spiro Agnew and Lyndon Johnson Watch the Apollo 11 Liftoff, 1969. Available from Flickr with no known copyright restrictions.