FreeLargePhotos.com is a website that matches its name. It is a collection of photos greater than 4MP that are free for use with attribution, except for selling products or promoting businesses or organizations.
If you are a photographer, note that they are looking for photographic contributions.
Of additional note: it seems the person behind the site is none other than Roy Tenant. Good work and a great collection of photographs, Roy!
found via ResourceShelf