I didn't click any of the links, so it's difficult to critique the images. #3 is my favorite, but It would be really nice if the subject was looking at the camera. The background color is eye catching and the composition works pretty well.
#1 - the subject's body disappears into the dark space created by the wall - next time try to get the subject to at least turn their head so that you get a little bit better light and definition. That kind of shadow can lend itself to some really dramatic images, so play around with it next time and see what you get.
#2. - reminds me of a kid dangling off the monkey bars on a playground - not especially flattering, and not really a good representation of the activity. Consider converting shots with splatches of color like this into black and white - that helps the focus stay on the subject and not the various handholds and such.
#4. Slightly disturbing. I have no idea what this is, but it's odd enough to catch my attention and make me wonder. The composition isn't helping it though, especially the bright blue V and the label. Perhaps consider cropping this in so that you get a closeup of the face and eliminate the distracting background and label.
