ConceptArt has a pretty good reputation. DeviantART does have some good artists, but they're rarities. The problem is that from what I know, there still aren't

ConceptArt has a pretty good reputation. DeviantART does have some good artists, but they're rarities. The problem is that from what I know, there still aren't many good art communities, if any. The best artists all have their own sites for that reason: there's no good common grounds. That's a wide-open, exposed field for possible startups: even Aviary focuses more on hobbyists and doesn't have plans to create more polished portfolio pages, from what I'm aware. It's one of those things where I figure if nothing's happened three years from now, I'll give it a shot myself: it would make a lot of artists very happy.