dancinghorse is having a mentoring sale through the 21st. She's a PhD from Yale, a former professor of novel-writing, among other things, at Wesleyan. She's an accomplished novelist in her own right, under three different names. And lest you think she's all about fantasy, Judy co-wrote a novel in Jerry Pournelle's War World series. With Steve Stirling and Harry Turtledove.
Details are to be found here: http://dancinghorse.livejournal.com/187431.html
Judy was a writer in residence when I went to Clarion in 1996. While I heart every single one of the six writers in residence from that year, Judy and I hit it off really well. Along with Greg Frost, she continued to take a personal interest in my work after Clarion.
What I do with Judy is the world-building stuff. I like the way her mind works. My worlds take me years to create, all their nuances. The past few times I've been there for a private horse camp, Judy and I have discussed what if this and what if that for hours about one of the several worlds I've been developing. I can't give specifics, because hey, that's in draft still. But she sees how a social society would grow out of the paradigms I propose.
For example, you propose a specific fact: all the horses and other beasts of burden have been killed/were not brought along/died of disease on a particular colony planet. There are no machines to do the work of these animals (lack of metals or whatever). What happens? How does this colony evolve? Does it breed or develop humans that will be beasts of burden? Does it change how they deal with things that might be heavy? Does it restrict travel? Do they try to breed dogs or cats to be beasts of burden? She will play with the science, the social aspects, anything. So far, we've worked in my science fictional worlds, not my fantasy ones. But she does the same thing there.
For others, she reads and comments on novel drafts. She looks at whether your characters are coming off the page, how your pacing is, your emotional tone. She seems to be really good at pegging a recurring issue that keeps a writer from climbing to the next level. Whether you can hear and apply what she says is a different issue.
But overall, Judy adapts to what you want out of the process. She's not judgmental about the material itself. She doesn't think about whether it's to her personal taste. She just lets go and looks at it in and of itself.
Oh, and don't take my word for it. Go read what kateelliott had to say, for example.