The group would be a moderated community where only I (and possibly other moderators) would be able to post. This would keep it from cluttering people's friendslists.
On Sunday or Monday, I would post a post where people would set a goal for the week. These goals could be phrased however you want, from "I want to write 5000 words this week" to "I want to complete a chapter this week" to "I want to write for six hours this week."
On Saturday or Sunday, there would be another post where people could say how far they had come in completing their goal for the week.
On the days in between, there would be posts where people could talk about how they were doing, ask for help, and otherwise discuss what they are writing. These posts will always have a concrit thread. Any member can post up to 4 comments worth of material per week to get concrit on. The focus of this community isn't crit, it's just encouragement, so really the idea behind getting feedback is to get help or get a question answered about something you're having a particularly sticky time with. Members will also be asked that they reply to at least three other requests for assistance in any week where they post asking for help. You'll be encouraged to give readers specific questions, such as "Does the narrator seem believable?" "Does the present tense work for this?" or "Is the transition in the third and fourth paragraphs happening smoothly?" This will help streamline everything toward specific help.
All media of writing would be welcome, of course. Poetry, articles, essays, fanfic, comics, whatever.
How does this sound to people? Do you have questions? What works? What doesn't work?