The best things seem to stay out of the mainstream and remain on the net as hidden gems waiting for someone to find. After an indirect tip-off, I came across MikeMeth on deviantART. He has some impressive work including a few Grand Theft Auto ones:
Awesome! If you have artwork of your own or come across something amazing, let us know or submit it yourself as a website member! Also be sure to find out about Grand Theft Auto 5 at the GTA 5 forums!