I'm more in revision mode right now, rather than writing mode, along with awaiting the editing of Marta's Pod.
If I move back into writing mode, a critique group such as this could be beneficial. I write Christian Sci-fi, and even was privileged to be a speaker at last years FW Conference on "writing outside the box."
As Deb stated, don't post chapters publicly. One, if more than a few excerpts of a story are posted on the 'net, publishing companies view that as "previously published," and will reject the submission outright without any other consideration (even if they're only posted here on the FW forums). The only way to get by that rejection, is if you self-publish and sell so many copies that the traditional publishing house decides your book will sell enough to offset the previous availability. Posting online can also open you up to having someone steal your work. You'll either need a protected sandbox page where participants can post their chapters, or, as Deb suggested, share them via email, with the added understanding that participants cannot share others' work with anyone else without the author's permission.
I'll keep an eye on this topic, though, and see how the group develops. If you end up one short, I'll rack my brain for an idea and get back to work.
Of course, I'm sure Eva and Marta will happily smack me upside the head to get me writing again.