There have been some examples of what NOT to do here on the blog recently.
Here's one that works well.
It works for a couple reasons:
1. it's funny
2. the tone is bright
3. there's not a single word of complaint in it
4. it's got some good solid tips for writers in the query process
5. It's funny.
And one of the things I like is that it shows you do get to break all the rules sometimes, and the query police not only don't show up at your house, if you write well enough you get an hour in the bar with the ever delightful Agent Lady (yes Diana, I intend to call you that now forever!)