If you haven't checked it out yet, there's a fantastic new deviantART group for you ctrlPaint readers! I want to thank Jingiss, Danny Roemers, and Owen Harvey for getting this thing together. They're holding weekly challenges, and have created sub-groups for critique.
It might be a small group now, but won't be for long. Don't you want to get in on the ground floor? Have fun, and happy drawing!
[UPDATE: 6/1/2012] Amazing! I'm really glad to see this taking off so quickly. It's great to see all of the art being posted. Can we make it to 500 members? Keep it up, everyone!
[UPDATE 2/11/2013] The community is still doing great, and is totally autonomous. I check in now and again, but it's run by the community. Check it out if you haven't gotten a chance yet!