Michael VanDeMar offers some great tips on how to find public domain images and creative commons images.
Sometimes I use Wikimedia Commons to find images, but it can be limited for choice. I'll try out Michael VanDeMar's suggestions on how to find such other free images.
If you can't find what you want for free, then I've used iStockPhoto.com to buy some great photos.
I've used istock photo when I have to buy something. Most times I make the images or take the photos myself. Sometimes I've had luck with creative commons as well.
Good thread. Would like to see if there are other ideas out there.
The major problem with free images is they come with providers watermark and you can not use them without marks, that is why i prefer buying an image for copyright purposes.