Book Four is:
Writing Great Books For Young Adults.
I got this book last year after AWP. I actually ended up going two hours out of my way (in the completely wrong direction) to the Barnes and Noble (I had a gift card), and yea...long story short, this book said, "Buy me! Buy me!" So I did.
To be completely honest, I haven't fully gotten through it, but it's set up so that it's easy to sift through and take what you want out of it. One of the huge things that I think was a stellar prompt was, 'What made your high school experience different from others?'
I thought back to my high school experience; I'd just changed schools, I was dating a boy in college (even when I was a freshmen), my best friend died, my sister's best friend died, the boy who showed me around school died, the boy who loaned me his pants died, my mom moved us into a trailer park, I went crazy and moved in with my sisters, I had to get surgery on my knee, I didn't drink, I was a rebel...(High school was NOT a good time for me, lol)
Bottom line, I was different in a million ways.
I remember feeling like an outsider, and having one friend who had my back throughout 90% of it.
And then I started writing, and what emerged was Character Defects. Now, every time I start to write something I think, "How is my character different," all because of this one prompt. Oh, and the best part? The author is an agent. She was at PNWA this year (though, sadly, I wasn't able to meet her).
The cost ranges $5-$15, but it is very, very worth the money.