I don't have any hard and fast rules, but I was thinking of a group that would be relatively committed to writing but still have those nagging day jobs. Ideally members would be able to read and critique something on the order of 6000 words (a chapter and a half or so)) weekly. Whose 6000 words would rotate.

If the group feels enthusiastic enough, we may add on any (or all, or none) of the following:
- Follow up crits: you critiqued the chapter, now see how the author has changed it to fit the group's ideas
- Chat sessions: talk in real time with some subset of the group about the work being critiqued this week. Finding an open schedule time for a group is an NP Complete problem, so this will be more ad-hoc.
- Larger Crits: If we've got energy, why not go for five digits (10K words / week), or more helpfully, crit 2 pieces per week so everybody gets to put their stuff up more often
- Character Interviews/Crits/IdeaFests: Spend a week bashing/critiquing/interviewing each other's characters
- World Creation Critiques: Talk about the fantasy/scifi worlds created in the stories

I'd be happy to serve as facilitator/email-nag-person, and would be able to find/create whatever collaboration technologies we'd need (if we do live chats, we should pick a common client with group technology, if we would like to create a private board and/or blog to serve as a community or see about starting a thread on Hatrack, etc).

If this does take off, people are welcome to join whenever, though I will institute a general rule of requiring a critique or two out of new members prior to putting their works in the critique order. In that spirit, as potential facilitator, I must therefore not have my stuff critiqued before doing so for two other people (though obviously that rule will be waived for the first N people to join, or else we'd have a dedicated but comically inactive group).