I'm going to focus this post on one member that I've found on 500px, Caras Ionut, and for good reason. Ionut has a very interesting style of creating images which involves several layers of post production to create a very deep atmospheric quality.
Every single image on Ionut's 500px page has a reason to be there. What I really like about Caras' style is that it doesn't really matter how the image is created (either via in-camera, or in post-production) as long as the vision gets completed.
Below is a sampling of some of Ionut's works, but please visit his site to check out those images that I haven't featured here (Each image will take you to the appropriate 500px page once you click on it).
Ionut offers some photoshop tutorials on how he creates some of these images. Feel free to click through to his personal website via 500px to see how each of these images is created. For instance, I found the image Vorex on his site to be a composite of 5 different images!
Of course, the only hassle is that the photoshop tutorials are priced individually (25 to 65 Euros) and are somewhat expensive if you get four or five of them.
Edit: A friend of mine from Romania has pointed out to me that while the 500px username may say Caras Ionut, Ionut is in fact this photograpers's first name. Error on my part, duly fixed. Cheers, happy weekend!