Image Resources
Below is a list of image resources. The resource outlet for images seems to be growing exponentially and looking for the right photo can take all day or many days. But it's usually worth if you find just the right one for your project. Please keep in mind that we can also create the image you're looking for with an illustration or a photograph.
Also, use any internet source with caution as the image may be copyrighted or may not be large enough or of high-enough quality to work in a printed book. Generally speaking an image for print must be about 4x's larger than it appears online because of a difference in dpi (dots per inch). A computer-screen image is published at 72dpi and a printed images is published at 300dpi. So when looking for an image for your print book think big or even huge. At Longfeather Book Design we love a big image because we can always go smaller with an image but it's much more difficult to go bigger. Although it is possible to fudge that a little bit, generally it's not a good idea.
Free Image Resources:
Wikipedia public domain images