Firstly, Congratulations and best wishes for this book.
My Question is more to share-out your part of interest like How you become enthusiast of this product and what attract you most in your first experience?
T.J., from what I remember, was originally into doing graphic design then got interested in programming. He originally worked with PHP, then Ruby, and then got into Node. T.J.'s written a ton of amazing modules.
I'm not sure about Nathan or Marc's stories about how they got into Node. I should ask them... it's always interesting how people end up doing what they're doing.