You may need to add some photos in your website, make it nice or give some massage to your visitors. Remember it affects to page loading time if you add many pictures in a page.

This site is free-photos site with large collection.

Home page tools
This site contains photos for web site development. You better read the terms of use before use them.

Webshots
Another collection of photos. Please read terms before use.

Elate
Here you find good collection of photos and background images.