Check out Zen Mind, Beginner's Mind for a good book on practicing meditation. It's not religious, but basically a transcript of a Zen Master's talks on zen and the practice of meditation to his group of students. It's what I recommend to people who want to 'get' meditation.

http://www.amazon.com/Zen-Mind-Beginners-Shunryu-Suzuki/dp/1...

Not specifically related to meditation, but The Tao of Pooh is still the best book I know of that deals with the concepts behind this stuff. I re-read these books whenever I lose my way, which happens more often than I'd like to admit ;)

Zen Mind, Beginner's Mind — Shunryu Suzuki [1]

Body by Science — Doug McGuff, MD and John Little [2]

1. http://www.amazon.com/Zen-Mind-Beginners-Shunryu-Suzuki/dp/1...

2. http://www.amazon.com/Body-Science-Research-Strength-Trainin...

I got started by reading Meditation in plain English: http://www.urbandharma.org/udharma4/mpe.html

I thought it was a pretty good intro. Not a scientific approach but there are some research papers on meditation. Have not run across a book.

I am now beginning to read Zen mind beginners mind: http://www.amazon.com/Zen-Mind-Beginners-Shunryu-Suzuki/dp/1...

Only just started so can't comment. Seems more advanced but I have heard great things about it.