There's also Newgrounds, I would honestly encourage artists to go back there if it was still chugging along as well as it use to be. It used to be such an insensitive site, and that trait was so strong that the most popular guys on the site were the most terrible (seriously, have you guys ever seen a review from Spazkid or Oney), so you always got so much critique. I've seen a bunch of kids who were doodling out their frustrations turn into professional artists that can have a stone face when being criticized. Though most of us have gone on to become Surgeons, Lawyers, Laborers and Policemen, I think the way it's structured in a way, while the system could easily abused, more often than not I felt like people grew as artists when they took the constructive criticism to heart.
A side note on the community:
Person A logs on to site
Person A: insert blatant threat here
Doesn't Post for Two years
Person A: "Oh, I have a kid now"
Person B: "Congratulations asshole"