This is an artist that I found in computer Arts a while back. His photo mantage stuff really is the business I think. I'm trying to do more montage work myself so I find this guy really inspiring.
He seems to just build up layer after layer until his work has this amazing sense of depth. I think that that is actually a really hard thing to do without making your composition seem really cluttered and overbearing.
Maybe the secret is to have patience and keep going back to the image with a fresh eye. Click to see site