I'm working my way through the incoming query letters tonight and there's some very good stuff to be found indeed.
What puzzles me though are people who send a query letter that is largely a review or a synopsis written by someone else. I see this a lot from people who have submitted work to contests. They start with "and my novel was nth out of n+100 and here's what PW had to say about it."
The purpose of a query letter is to read YOUR writing. I know the editors at PW can write. I also know they aren't looking for agents, and they're really not looking for agents for YOUR book.
Write your own damn query letter. All of it.