Online Digital Image Collections

Anne Blecksmith at CR&L News compiles a listing of seventeen digital image collections available on the Web from universities, public libraries, historical societies, archives, and Library of Congress, including the New York Public Library Digital Gallery with over 600,000 digital images.

To those, I’ll add a couple of places that I visit to find hi-res images:

ARS
ARS - Agricultural Research Service image gallery with over 2,000 hi-resolution photos available for download free of charge in subjects such as crops, animals, and insects.

Galaxy
GRIN – Great Images in NASA is a resource with over 1,000 hi-resolution photographic images available free of charge in subjects including space, aeronautics, and Soviet Spacecraft.

NOAA
NOAA – National Oceanic & Atmospheric Administration’s collection of over 30,000 hi-resolution images in albums such as the Coral Kingdom with underwater images of plants and creatures and the National Sever Storms Lab with tornado and other storm photos.

Baby Eagles
U.S. Fish and Wildlife Service National Image Library – Thousands of free, hi-resolution photographs of wildlife and plants.

Elvis
NARA Online Exhibit Hall – The US National Archives & Records Administration offers some great photos from American history.

DefenseLink
DefenseLINK Multimedia Library – Hundreds of military photos available for download in hi-resolution.

For more, the Digital Librarian provides a descriptive list of hundreds of images archives available online. And you may want to check out these helpful blog posts:
Find free images online!
Where can you find good images?

Please list your favorites in the comments!