The Mind Illuminated: A Complete Meditation Guide Integrating Buddhist Wisdom and Brain Science by John Yates (Ph.D.). This is the best book I've read on meditation. It takes you through why it works, how to do it, how to keep improving at it, and all the common pitfalls you'll encounter.
I take a bit of issue with this idea in general that because something has worked for thousands of years, we shouldn't try to apply modern ideas to it. In this case, I think for the actual practice of mindfulness, it's mostly true that helpful technology aids are ironically unhelpful, but building a habit can be hard. Apps like Headspace and so on help a lot of people build the habit.
Seconding the book recommendation -- it's by far the best book I've read on the topic too.
I bought one of those $300 headbands that "monitored your brain wave" while meditating and had all the apps. A chapter or two into the book I realized how ridiculous it all was. They might have helped establish a habit, but I was never going to progress very far while using them.
That's not the point Lom7 made. Some "modern ideas" like neurology seem to go very well with meditation. Some.
What I personally take issue with is the idea that mindfulness and enlightenment can be boiled down to 10 min intervals without even having to remove your earbuds.
I'm glad more and more people are getting into mediation and seeing the benefits, I just hope that developing mindfulness as a skill doesn't get lost in the app-of-month trends.
http://www.vipassana.com/meditation/mindfulness_in_plain_eng...
Yates also makes the admirable choice of retaining traditional terminology and outlook in cases where modern science wouldn't have anything useful to add (he resists scientizing, in other words.)