I think it's always fun to look at rough drafts and other prototype-ish stuff, as in early sketches that an author made while playing around with ideas, and other interesting things like that.
Below are some scans of a short manga series by Akira Toriyama, titled Dragon Boy, which are prototypes in the sense that the similarity to Dragon Ball is so strong.
Wow, that's pretty cool! I've never seen that before. The only thing I can think of that's similar is the Sailor V manga, although that actually became a part of the Sailor Moon series since she was Sailor Venus.
I love stuff like that. I think One Piece has a prototype story as well. What I really love though is seeing process and concept stuff, but that's certainly more rare.