Back on livejournal we had a community called ArtSlam and I've since made a mirror of the community on dreamwidth. artslam. As for what it is, here's the general idea:
"ArtSlam runs from June 1st to August 31st, providing a summer-long challenge that is simple on the surface: draw something every day. For this community, we prefer that you pick a concept and stick with it for at least one month. If you have a world that you want to explore with art, or a set of characters, this is a great place to do it! If you're shaky with perspective, background art, anatomy, or just really want to draw 30 pandas, you can hone your focus that-a-way, too."
So if you're looking for an active community this summer with feedback on your progress or world building and want to dive into it, please join us!
Sign Ups are here: http://artslam.dreamwidth.org/1942.