I learned many alternate spellings while solving those things. ;-)
Your question piqued my curiosity and I found a cool explanation of the origin of "gizmo" at answers.com
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gizmo
Origin: 1942
How did we win the war? Well, we had the right gizmo when we needed it. The term is an honorable American invention, like doodad (1877) and doohickey (1914), the latter a Navy word that helped us win World War I. A couple of decades later, when we had to make the world safe for democracy all over again, we added to our arsenal both whatchamacallit (1942) and the modern gizmo.
Nobody knows where gizmo came from, but we think the Marines told it to us. The evidence is from two articles, both published in November 1942. Leatherneck magazine explained, "When you need a word for something in a hurry and can't think of one, it's a gizmo." And Yank that month agreed: "Leathernecks...even have a name for a whatsis. They call it a 'gizmo.'"