All right, I'm gonna pull upon the cloud here, and I'm gonna go to my archive, and let's see what I can find in here that I have outlines for that I haven't written.
There's one I know of for sure. I'm not gonna tell you what that one is. It's a secret project. One that I haven't talked about.
I don't know if we count Death By Pizza. I have a full outline for that. But that's a book I didn't write, and then I passed the worldbuilding off to Peter Orullian, who was writing a book based on it. Not using my outline, because the outline had some problems. But that would probably be number two.
Dark One became a graphic novel. So I don't know if you count that. That's, like, half of one.
Starburner would be number four-ish. That's the first full outline that doesn't have a book attached to it right now.
Don't know if you count Stormlight Five. The outline for Stormlight Five is very detailed. Six through Ten is less detailed; I do have them, but they're more like a paragraph or two about each book, so I wouldn't count them as a full outline.
Five in my "Novels to Write Someday" one. Which, most of them, you guys haven't heard about. One's the magic that uses kites; I've talked about that before.
I've got "Totally Not A Rewrite Of Episode I" that I wrote nine years ago. I just could not help it.
I have the five I mentioned earlier. In addition, in their own folders, I have I Hate Dragons. (Which I actually outlined the whole I Hate Dragons book, but I only wrote the little piece of it that was a writing exercise.) I have... six.
Six plus five, so eleven outlines in my Novels to Write Someday. And then two half ones that I passed on to someone else. And then all the Stormlight and Mistborn and things like that that don't quite count. So there you go, eleven. It's eleven only, right now. That's not very many. I would say that I've got at least that many in my head, maybe a few more.
Oh, and Secret Project, so that's twelve. And all of those are Secret Projects in a way, I guess. You've heard about some of them. One of them is The Lurker, which became Adamant, which I wrote one novella of, but I have the outlines for the rest.