Click Clack Moo is a book I'll have to add to Finley's library. On the blog Collecting Children's Books, there's an excellent post about children's books, their authors, and typewriters.
"Norma Fox Mazer's first novel, I, TRISSY, concerns a girl adjusting to life after her parents' separation. In the opening scene, Trissy's father gives her a typewriter ("Tris, now you can put down on paper all the things you're always making the mistake of saying out loud, and nobody has to know about them except you.") The book is printed in a font that mimics typewriter print, contains typed "pictures," and even includes strike-overs and other typing errors." I remember reading this book!