Large photo gallery with 7000-1000 new photos uploaded monthly. Photos on Photl are exclusive to Photl, so you won't find any repeats from other stock image sites. You are permitted to download up to 40Mb per day. There is a small fee if you are using any pictures for commercial use.
Photo library from the National Oceanic and Atmospheric Administration (NOAA). Photos are very easy to download, but not very easy to search (must search by collection and sometimes the title can be deceiving of contents).
Lots of high quality photos in a variety of categories. Please note: this website is about to move to another hosting provider, so you may have to Google "Open Photo" if this link is broken.
Search millions of photographs from the LIFE photo archive, stretching from the 1750s to today. Most were never published and are now available for the first time through the joint work of LIFE and Google.
If only every website had a "Copyright Information" page as clear as this websites. Please note that while these images may be used for educational purposes, they may not be altered.
This website was created by an educator, for educators. Mr. Vann clearly states that his photographs and drawings are free for use without permission. Images are organized according to subject area.
Similar to Creative Commons, Luna Commons is a digital collection of images, audio, video, etc. to be used for educational purposes. The search interface is not as user-friendly as Creative Commons, but the amount of content available is immense.
Wylio is a search engine that browses images with Creative Commons licensing. This website was originally created for bloggers to find pictures. The free version allows you to search, resize, and embed the code (with credits) into your presentation. The subscription version ($2.99/mo) allows you to specify pixel size, download, and remove ads.