So I guess a true measure of a photog's skill is how good the pic looks before the re-touching. Kind of like how beautiful your girlfriend is first thing in the morning without her make-up. 
Apart from the obvious HDR shots and B&W, most of the others have only had a slight increase in contrast applied. All digital images require some sort of post-processing, sometime this is applied in-camera, sometimes not.
It's funny how people assume that post-processing or retouching are somehow cheating (not accusing you Jeff, but I do get it all the time), 99.9% if images used in any media have been processed in some way, yet when you are an amatuer it's as if people think you shouldn't do it for some reason. It's far easier to get it right in camera than to try and process it to look good. I managed to get most of these right first time, which made life much easier and I was able to get them all done in the same evening, that Alfa shoot took me about a week to get through them all!
Bear in mind many of the editing tools available in photoshop like dodge and burn etc. have been using in photography for decades, that's how they got their names in the first place.
http://en.wikipedia.org/wiki/Dodging_and_burning 
I can't remember the guys name but there was a photographer from the late 1800's/early 1900's that used to draw on his negatives with pencil, thereby 'shopping in new characters, trees etc.
Saffy, HDR is High Dynamic Range, meaning you take mutiple exposures and get the light detail from the dark shots and the dark detail from the light shots and combine them either manually or in software to create an image with more dynamic range than you can achieve in a single exposure. If done using HDR combining software such as Photomatix you can choose for the effect to be as tame or as wild as you like.
couple of examples:
Dark Shot
Middle Shot
Light Shot
Combined example
To give you an example of the different levels to which you can apply the effect, this is obviously HDR:
And so is this:
