Image Search Engines
Google Image Search: Google’s huge database will help you find pretty much any image on any topic that you can think of.
Image Search Sites
ImageAfter: “You can download and use any image or texture from our site and use it in your own work, either personal or commercial.” Wide variety of images here.
Stock.xchng: This is the first place I go for images on the Web. There are varying licenses with each image, but most are completely fair-use.
Flickr is a great place to go to find a huge array of different photos. Make sure you check if the photo you want to use is available; not all Flickr users give this kind of permission.
IStock (from Getty Images) Stock photos and royalty free images.
*Note: please read the fine print before using images from any of these image search engines or image search sites. Different photos and sites have different usage licenses, which can possibly restrict your use of their image. *