As a former Vipassana practicioner, I bought and enjoyed the Mental Development book. Short and to the point; helped me to start meditating again after several years of hesitation or a "dead end" of sorts. The tone and style of your writing have an interesting "math-y" feel -- but it also feels very clean and somehow calm.
Same goes for the Klong book, which I bought and enjoyed thoroughly. Haven't mastered the language, though, but I'm hoping to; it definitely is really interesting, especially for a person like me who loves the build-your-own-tiny-tools-with-tiny-languages-for-your-own-use-and-prefer-low-end-computers philosophy. I'm definitely a fan of your work; your webpage and entire way of life has been an inspiration for me for years already.
If you don't mind me asking -- are you working on any upcoming books these days as well?
would you mind me asking what motivates you to write as much as you have? just writing one book is bucket list item for me, yet here you've written >= 13! do you write for an audience or is it perhaps primarily to consolidate your thoughts?
I have written much more, more like 20, but not everything is still available. Then with a few books I ran out of motivation, so they just sit in my archive.
At the beginning writing somehow fascinated me, but right now it is probably just habit/momentum/karma that keeps me going.