These are all resources that provide access to copyright/royalty free images:

• http://search.creativecommons.org/
• Compfight
• Flickr Creative Commons
• Free Digital Photos.net
• Library of Congress on Flickr
• http://www.loc.gov/pictures/
  
• U.S. Government Photos and Images
• Wikimedia Commons
• From Rapid E-Learning Blog, Here's How to Find Free Stock Photos & Clip Art for PowerPoint
• http://www.123rf.com/
• Liam's Pictures from Old Books for something different: http://www.fromoldbooks.org/
• http://www.morguefile.com/
• Metropolitan Museum of Art
• The best free stock image resources on the Web
• http://www.bing.com/images?FORM=HDRSC2
• http://www.smashingmagazine.com/tag/freebies/
• http://www.gettyimages.com/creativeimages/royaltyfree
• https://images.google.com/?gws_rd=ssl
• http://pixabay.com/en/
• Buffer blog post on image sources: https://blog.bufferapp.com/free-image-sources-list
• http://deathtothestockphoto.com/
• From Alaska State Library, http://lam.alaska.gov/freemultimedia
• http://www.gratisography.com/
• http://picjumbo.com/
• http://unsplash.com/
• http://littlevisuals.co/
• https://openclipart.org/
• Whoa! Check Out These 78 Free Sources of Images For Your Library on Making It Happen
• https://www.wylio.com/
• Free Stock Photos that Don't Suck
• Makerbook, A hand-picked directory of the best free resources for creatives
• On Library Market, http://www.librarymarket.com/services/dropbox Formerly known as "The Library Facebook Images Dropbox," this is a collection of images to help libraries increase social media engagement with patrons.