Although there are numerous digital art sites across the internet, the other day I stumbled on one in particular that is pretty interesting. It's called Concept Art World. My only comment is that when I see some of the incredible work that these artists create, it suddenly becomes easy to write stories. I've said more than a few times that I could probably outline a novel or write a short story in a matter of hours based on a single concept art image alone.
Another great site for inspiration is Feng Zhu's blog and his associated FZD design school channel on YouTube. Check it out...there are many very informative videos there.