After completing my PhD in cognitive psychology, I wrote The Memory Key, which was published in New Zealand in 1999. It was subsequently published in the United States, then translated into German. More recently, it was revised and republished by Random House UK as Perfect Memory Training -- which has now been translated into French, and is available as 100% mémoire.
The Memory Key was my 'foundation stone' -- it sets out the general principles that you need to know in order to achieve long-lasting memory improvement, and provides an overview of the many useful strategies that can help you improve your memory skills.
The Memory Key was followed by this website, which I have maintained since 2000, and then by various books on specific memory skills. The first of these, on how to remember your intended actions and events (appointments, anniversaries, errands, ...), was recently expanded and updated to include advice on dealing with those absentminded slips we are all prone to, such as forgetting what we're doing, or whether we've just done something.
All my books, as well as some shorter digests of material that's been posted on the website over the years, and some free collections of website articles, are available in digital format (pdf, ePub, mobi - all DRM-free) in my store. The books, in the appropriate digital formats, are also available at Amazon's Kindle Store, and Kobo's Store. They are also available at Amazon as paperbacks (see the images below for individual links).
The first row of images will take you to individual product pages on my website, with more details about each book.