Just came across these which were drawn by other Mangaka such as toriyama, kishimoto, kubo and others. Where drawn for a 10th Anniversary issue a couple years ago anyway here they are. Smoe of them are really good.
Akira Toriyama - DragonBall / Dr Slump
Masashi Kishimoto - Naruto
Tite Kubo - Bleach
Takeshi Obata - Death Note
Yusuke Murata - Eyeshield 21
Chase Murata - Neuro
Yoshio Sawai - Bobobo-bo Bo-bobo
Takehiko Inoue - Slam Dunk
Kyosuke Usta - Jaguar
Hideaki Sorachi - Gintama
Mitsutoshi Shimabukuro - Seikimatsu Leader Den Takeshi!
Takeshi Konomi - Prince of Tennis
Akira Amano - Reborn!
Katsura Hoshino - D. Gray-man
Kentaro Yabuki - Black Cat
Mikio - Some harry Potter Thing
Kiyu - Number 10
Kanou - Mx0
Ejiri - P2! Let's Play Pingpong