Open Source Libraries

Veezzle - Free stock photos
http://www.veezzle.com/

Morgue Files
http://www.morguefile.com/archive/
The morguefile free photo reference archive provides the public and creative community with a repository of free raw photo materials.

Fotopedia
http://www.fotopedia.com
An Online Encyclopedia for Photos

Open Photo
http://www.openphoto.net/

Copyright free images
http://collaborationnation.wikispaces.com/Photos

Stock xchng
http://sxc.hu/

PicApp
http://www.picapp.com/
Photos of celebrities etc - free of copyright and free of cost.

Discovery School Clipart Gallery
http://school.discoveryeducation.com/clipart/

Compfight - Creative Commons images
http://compfight.com/

Wylio - creative commons images
http://www.wylio.com/

Flickr Sets

David.l.Quayle's photosets
http://www.flickr.com/photos/16236990@N08/sets/
Photos of  different countries

The Commons
http://www.flickr.com/commons

Sydney's Powerhouse Museum
http://www.flickr.com/photos/powerhouse_museum/

Archival / Historic Photo Galleries

Photos of  Space - NASA
http://www.nasaimages.org/

Brian Seed Fine art
http://www.brianseed.com/Hong_Kong-Historical_Engravings/c32_34/index.html

Gwulo - Images of HK - sorted and searchable
http://gwulo.com/photos-of-old-hong-kong

World Digital Library
http://www.wdl.org/en/#

NY Public Library Digital Gallery
http://digitalgallery.nypl.org/nypldigital/

LIFE photo archive hosted by Google
http://images.google.com/hosted/life

National Australia Library  Digital Images
http://sbdsproto.nla.gov.au/sbdp-ui/island/picture

Picture Australia
http://www.pictureaustralia.org

NZ Timeframes visual history database of NZ & Sth pacific
http://bit.ly/OZuUz

British Library Iimages Online
http://www.imagesonline.bl.uk

Cultural Images of Eastern Asia 1907 - 1927
http://bit.ly/2tjtY

World Press Archives - over 10,000 images
http://www.archive.worldpressphoto.org/

Historigrafica
http://www.histografica.com/

V like vintage
http://www.v-like-vintage.net/en/home

Visualising China - 8000 digitised images of photographs of China taken between 1850 and 1950
http://visualisingchina.net/