There is a great resource for artists at http://www.morguefile.com/. There are landscapes, bridges, models, animals, flowers, insects, just about anything you are looking for and with no copyright issues; the photographers are sharing their work. It's a lot of fun to just go on the site and search for things.
I especially enjoy the beautiful pictures of birds since I don't have anything close to the equipment or skill to take good pictures of them but I like to draw them. The first image above is one of my favorites and the first that I’ve experimented with. It, like many other wonderful images in the Morgue, is by photographer and IT professional Scott Liddell. You can learn more about Scott on his blog at http://www.scottliddell.com or view his wonderful photography at http://www.scottliddell.net. I took Scott's image into Illustrator, made a modified vector trace of it and then enhanced that view in Photoshop (the second image above).
There are no copyright issues when using images from this site. But when you use images from www.morguefile.com be sure to scroll down to read who the photographer is and if they want to be notified if you use their images. Scott did, and so I did.
