This from eSchool News:

“NASA Images” is a service of the Internet Archive, a nonprofit digital library. It was created under a Space Act agreement to offer unprecedented access to NASA media (including images, video, and audio), functioning as a free online library for all of NASA’s multimedia content. Users can search for material by keyword or theme (such as Earth, Astronauts, Solar System, or Universe), or they can browse through several featured collections. The site is constantly growing with the addition of current media from NASA, as well as newly digitized media from the archives of the NASA Centers.
Go to http://www.nasaimages.org to see for yourself!