I think I've seen this link before, but there's a great site for license free images called everystockphoto. They currently have over 268,000 free images for download. Definitely worth checking out if you're doing a project on the cheap and need some images to use.
On a related note, iStockphoto is site were you can get very inexpensive photos (from $1 to $5 per image, based on the resolution you want.) The great thing about this site is if you're a photographer, you can sell your pictures on this site. A acquaintance of mine, Todd Smith of SaturatedPixels has been selling his works there for a couple of years. Check out his iStockphoto portfolio.