I have set many formal tables throughout my entertaining years so far, but I always seem to forget where items should be placed. This is an awesome reference to have bookmarked!
This article on Entertaining With Style (blog covering all things entertaining related) provides readers with a graphic and coordinating numbered list of where each item should be placed when setting a formal dinner table. I think this is so helpful for those who set formal tables often, or even rarely. Go ahead...impress your Mom and have her over for a formal dinner (you don't have to tell her about the cheat sheet you used).
I think this article clearly demonstrates where each piece of cutlery and china should be placed however, it does not provide any variations which could be helpful. It would be a more helpful resource if it outlined different cultural variations and/or levels of formality. I mean do we always need that many spoons? Really?