Links to some (apparently) public domain stereographs

• http://www.exploratorium.edu/history/PPIE-3D/index.html Panama Pacific International Exposition, 100 stereographs, copyright 1915. Original scans plus red-cyan anaglyphs.
• http://www.history.navy.mil/photos/arttopic/stereo/stereogr.htm
• http://www.lib.unc.edu/ncc/pcoll/43stereo/ A collection of miscellaneous stereographs made in North Carolina from circa 1870 to circa 1904. The policy page state that you must execute a usage agreement with UNC. I don't know if this requirement is binding on public domain images, so use these at your own risk.
• http://www.greatwhitefleet.info/Rose_Stereographs.html Rose Stereographs. One is animated. Most of the cards are warped. Copyright 1908.
• http://rs6.loc.gov/pp/cwphtml/cwpstereos.html Library of Congress Civil War stereographs.
• http://www.hazyhills.com/mars3d/ A collection of stereo images from NASA/JPL, from the Mars rovers. Interesting presentation where each pair is displayed as 3 images so one can choose to view cross-eyed or parallel by looking at the left 2 or the right 2 images. Anaglyphs are also presented.