Puisque la question a été soulevée dans Twitter, voici une liste de sites proposant des images libres de droits ou disponibles sous des licences de type Creative Commons..

http://commons.wikimedia.org/wiki/Main_Page

http://www.freephotobank.org/main.php

http://www.photo-gratis.com/

http://www.freefoto.com/index.jsp

http://www.dexhaus.com/v2/

http://www.kavewall.com/stock/

http://www.adigitaldreamer.com/gallery/index.php

http://www.stockvault.net/

http://www.freephotosbank.com/

http://www.freedigitalphotos.net/

http://www.cepolina.com/freephoto/

http://www.turbophoto.com/Free-Stock-Images/

http://www.freestockimages.net/

http://stockart.deviantart.com/

http://www.stockvault.net/

http://www.unprofound.com/

http://www.vintagepixels.com/

http://www.openstockphotography.org/

http://www.imageafter.com/

http://www.fontplay.com/freephotos/

http://www.everystockphoto.com/

http://www.photocase.com/en/

http://www.sxc.hu/

http://www.graphicsarena.com/

http://www.morguefile.com/

http://www.flickr.com/creativecommons/

http://www.fromoldbooks.org/

http://www.pixelperfectdigital.com/free_stock_photos/

http://www.mayang.com/textures/

http://www.woophy.com/map/index.php

http://www.woophy.com/map/index.php

http://freerangestock.com/http://www.designpacks.com/

http://www.zurb.com/zurbphotos/

http://www.diwiesign.com/index.php?page=stockphotos

http://tofz.org/index.php

http://www.animationfactory.com/en/

http://www.burningwell.org/

http://amazingtextures.com/textures/index.php

http://amazingtextures.com/textures/index.php

http://www.fotogenika.net/modifica/igallery.asp

http://www.freemediagoo.com/

http://majesticimagery.com/

http://www.photoshopsupport.com/resources/stock-photos.html

http://www.creativity103.com/

http://www.texturewarehouse.com/gallery/index.php

http://www.geekphilosopher.com/MainPage/photos.htm

http://www.afflict.net/

http://www.creatingonline.com/stock_photos/

http://freestockphotos.com/

http://www.freeimages.co.uk/

http://www.lightmatter.net/gallery/

http://www.artfavor.com/

http://www.insectimages.org/