How are these effects done

Hello all, new member here! I am looking for insight on how I can acheive this effect for my digital photography.

Although many of these look like they are made in Maya or 3DS they are in fact real people. This is a 2 part question, first is where does one find larger format high res backgrounds like those in the links below and most importantly how can I make my subjects look like they are on a poster.

If anyone knows how this is done that would be great! I am at a loss!
What programs were likely used?
Plugins?

Here are some links to a phenominal artist and photographer:
http://img5.modelmayhem.com/061127/15/456b5aaf7d738.jpg
http://img4.modelmayhem.com/061017/13/45351ab130bc0.jpg
http://img4.modelmayhem.com/060427/06/4450b092d7992.jpg
http://img1.modelmayhem.com/051209/12/439a1c59b3538.jpg
http://img5.modelmayhem.com/061220/14589c415cb9e2.jpg

And here is another artist as well, go to gallery and you will see similar effects.
http://www.studiobild.com:80/

I really appreciate any help on this.

Thanks!!
SN

Actions just make it faster to do the same thing. Along with some masking and layer blend modes and done. If you have some similar photo let me know. Lighting is very important or these shots. I can add highlights but if the are from lighting/camera that is better. Peace