What? Did you think I was going to tell you how to write a fabulous query letter? I'd rather slay a Jabberwocky. But you could always check out Writing World.
Seriously, check it out.
My marvelous agent Natalie Lakosil's template for a good query letter:
She also included a link on Query Tips:
Or you could ask author/former literary agent Nathan Bransford about the "anatomy of a good query letter."
I'll be posting additional links as I find query letter examples that I believe are helpful.