My second-favorite line in the Harry Potter books: "I like a healthy breeze around my privates, thanks."
In The Goblet of Fire, two other things worth noting: Here, again, Rowling is excellent at introducing things early in the book in such a way that I, at least, did not notice on a first reading that something was being set up for later use. I'm thinking of the portkeys, which are so integrated into the story of the Quidditch World Cup that they do not cast any shadow of foreshadowing, and when Rowling needs the portkey at the end, she just uses it, without needing to explain a thing.
Secondly, this, after Harry tells Dumbledore that Voldemort used Harry's blood to rejuvenate himself: "For a fleeting instant, Harry thought he saw a gleam of something like triumph in Dumbledore's eyes."
I know, I just implied that Rowling does not foreshadow, but that seems like a pretty major teaser to me!