Ayya Khema's framing of key Buddha's teachings as the natural way for the mind to go as it quietens is something I find very empowering. It helps me to approach the Buddha's teachings not as mysterious or accessible only to a few who have particular qualities or abilities, but rather as available to all those who practice diligently. It is a straightfoward and very encouraging message.
Ayya Khema led retreats all over the world until her passing away in 1997 at the age of 74. Having ordained at the age of 56 and therefore having had a relatively short monastic life, the depth and clarity of her teachings are nonetheless extraordinary. You can listen to a number of her talks at AyyaKhematalks.org, where mp3 recordings can be streamed or downloaded.
The Forres Dhamma Friends group has a number of links to her talks at their Forres Dhamma Friends facebook page.
Ayya Khema's senior student, Leigh Brasington, maintains an active retreat schedule. His recently-published book on Right Concentration is also highly recommended.