I've went through the Sandman series, but other than that, I don't know his work too well. Could a more informed fan tell me what they think his magnum opus is?

Please remember that you asked. And that this is all my own opinion, not backed by any verifiable (sp? I'm too lazy to check my spelling right now) scientific data.

I think that of his "adult" novels, American Gods is a stunning achievement. This doesn't mean it is flawless.

Of his "kids" stuff, Coraline is wonderful, but I think that his new one might rank up near the top as well.

Of his shorter works, The Dream Hunters illustrated by the great Japanese artist whose name is sadly escaping me is unbelievably beautiful. He has several short stories scattered throughout his collections that are freaking amazing and deserve many rereadings -- please, read them now now now, with caution and delight.

And of all his comic books, I think that Mr. Punch is perhaps his greatest. An amazing, thought-provoking and heart-wrenching story that stay with you for days.

(if you want specific names of short stories, I can do that, but I will save you the time and encourage you to read all of them and decide for yourself! )

I think it has yet to be written. He's not done yet and that is rally thrilling to realize that we have years to come to enjoy all that he writes.