I think some of you may have misinterpreted what Concept art is; so here's Wikipedia's definition

Concept art is a form of illustration where the main goal is to convey a visual representation of a design, idea, and/or mood for use in movies, video games, animation, or comic books before it is put into the final product. Concept art is also referred to as visual development and/or concept design. This term can also be applied to retail design, set design, fashion design and architectural design.

I wrote an essay on some concept artists for college recently(Which I'll upload if anyone wants it), and in researching it I thought it was really cool.
I'll post bits of it to show some work I really liked;

Here’s a comparison of some concept artwork of the iconic bus stop scene in My Neighbor Totoro (1989).  The image on the left was probably created early on in development, as the storyline must have influenced whether there was one or two of the children there. But we can see how close this artwork is to final shot. This must have been a bold image in Miyazaki’s head and it proved it’s worth as it’s such a memorable way to communicate this scene.

Another of Miyazaki's showing this setting from Spirited Away


This artwork was by Chris Appelhans, I love the work he did for Coraline, that takes his interpretation of Tadahiro Uesegi's artwork and builds his ideas about the styles and textures and colours.
It's awesome

Any of you guys got some favourite artists you've been looking at?
Oh! I forgot to mention Ross Stewart, who did concept art for The Secret of Kells, go look it up, that film looks like nothing else!