here's the scenario. if someone asks me to design a world of warcraft site. I get the wallpapers and fanpack they have and used it as images to create the site. then they pay me. that's illegal? @hman dude, of course i get all the images on wallpaper downloads and fan pack. why would i get images right of the site. it will be hard doing screenshot and cutting.
Of course it's not illegal. It only becomes a problem if you are infringing on things like trademark, or using images or other content that you don't have a right to use, or show. There's a ton of material that is out there for you to use legally. You just need to stay away from proprietary material that is not meant for reproduction or distribution. For instance, I get links to downloads all the time of albums and tracks before release. They are for me to listen to and maybe even review, but I have no right to make that link available to the public. When you breach that trust that you are not a responsible webmaster, that's when people want to sue you. If you stay within the boundaries, you will find, not only will people help you but they'll keep you on top of their press list to get new material and free stuff for review before others. If you go off on your own and don't respect the rights of the company, not only will you be operating in a vacuum, but that's the kind of stuff that makes people want to sue you. Trust me, there are more images and videos out there, put out by the company, or authorized for use by sister companies than you know what to do with.
You can take a regular stock photo or press image and photoshop a dynamic background or other effects and make it original. You just have to be creative.