This is one of our favorite sources of royalty-free photos. Includes a lot of stunning scenery from around the world but also useful portraits of people, objects and animals. A good quality library which is growing all the time.
An extensive library of over 660,000 images, including illustrations and vectors, as well as videos. Covers the widest range of good-quality images we've seen in a free image library including some useful portraits and objects. Be aware it also displays panels of Shutterstock commercial images.
Another excellent site with a very wide range of material including business-related images you might find on commercial stock photo sites. Cteaed by the people behind the graphics editor Snappa.
A gallery of whacky and whimsical photographs taken by Ryan McGuire of Bells Design. If you want something out of the ordinary this is the place to look.