mav (et al),

I nearly jumped into this one with both feet, but then took note of your plea for "reflection time". and then, the more I reflected (and saw other's responses), the more I thought that I wasn't getting at the "formative experience" part of the question. furthermore, in reading the proferred lists, I had to ask myself "was this really the sort of stuff I read during my formative years?" (which I take to mean those writers and that work that profoundly influenced my use and abuse of language today)

so my list (there's no way that I could do "ten") would include a whole bunch of science fiction (Asimov, Heinlein, Bradbury... later to include Tolkien and other fantasy) and adventure (Jack London, Twain) and Civil War (Bruce Catton) and Hemingway and Fitzgerald, and Salinger, Kesey, Heller and Vonnegut, and so on; until by the time I got to Shakespeare and James Joyce and Gene Wolfe and all my other latter-day saints, I was probably beyond being saved.

oh, and I almost forgot the Usual Gang of Idiots (®Mad).