Looking for that Wow Factor. Can you Help?

I read a lot. I mean, what writer doesn't really? But you know what? Most of the books I've read lately are missing that Wow Factor. You know the feeling: you can't put the book down. Who cares what else is going on in the rest of the world. You must finish that book!

What gives?

So here's my challenge to you: what's the last book you've read that gave you that Wow Factor? Would you mind sharing it? Because I'm sick of reading so-so, a-okay novels.