A few people have mentioned the CYOA Cave of Time map. That's mine. I created it as an example of a narrative map (along the lines of what Marie Laure-Ryan describes as "structures of interactive narrative" in Narrative as Virtual Reality). The map was part of a project I assigned to my students at George Mason University; you can see the full Choose Your Own Adventure Analysis assignment on my course website.

I must add that my assignment, and the whole idea of mapping a CYOA book was adopted from a very similar idea by Professor Matthew Kirschenbaum at the University of Maryland, College Park. I imagine that most of the CYOA maps you'll find online were inspired by Matt's original assignment.