Thanks for that link. Wonderful images.
There seems to be many different techniques involved and only some would be photoshop related. Obviously he is a very skilled photographer, and one of the reasons that the images looks so great is that he can shoot each element, in the ones that are composites, himself, so they will fit together.
Its a lot harder to take parts of different photographers images and try to bring them together because they maight have been shot with a different lens, angle, color temperature and so on. Careful planning would be the key to get images like this.
On the other hand , the guys at
www.worth1000.com makes wonders just using stock photos.