There's a great posting in this site about a 34-volume collection of the Dragon Ball manga featuring art from different mangakas.
"In 2004 the Dragon Ball manga was re-released as a 34 volume collection instead of the initial release of 42 volumes. This new release named Kanzeban was bigger than the old edition, with new covers and an altered storyline. But the best part of the Kanzeban is the artwork that comes with the book. What is so special about this artwork? The fact that it is drawn by other mangaka; mangaka that have been influenced by Akira Toriyama’s work in the past."
Go check it out. The sample above is made by the creator of Naruto.