I have noticed that nearly all religions that are based on a kernel of truth have all had mystical sects which have creatively tried to understand the heart of the religion to which they have had their inspiration from.
So for Christianity there have been the Gnostics. These guys base their understanding on the supreme state of consciousness which can be attained by the Gnostic monk, which is called "gnosis" and is also referred to as "Christ consciousness"- the higher level of concsiousness which is said to have been attained by JC.
The Buddhists have Zen, an extremely creative school of training which focuses on the attainment of enlightenment by the monk. Zen is said to be like a brick which smashes its way through the normal ken of understanding via the use of koans, non-sensical riddles which the monk is supposed to find an answer to while meditating. Also the master of any Zen sect will always emphasize the Zen in everything which cannot be seen except by one who is well trained or just damn lucky. Apparently all monks who are ready for enlightenment will pass through a state of awareness known as "The Moment of Great Doubt", beyond which they finally find their own "seat of enlightenment" , never to return to our normal state of consciousness , where enlightenment is seen as final and permanent - however it is stressed that there is no end to learning.
Islam has the Sufis, who are known for their whirling dervishes, their amazing mathematical description of the universe via their unique diagramatic art as well as their amazing poetry and other unique insights.
The hindus can relate to Zen, as they can to Buddhism.
Does anyone know of any others?
I have always found these mystical sects as the most potent realizations of these religious traditions, always adapting to their surrounds, the cultures and relevant time periods. So Japanese Zen will differ from Chinese Zen, in accordance with the different backgrounds they inhabit. They must remain relevant and vibrant to include all the new generations that are to follow, lest they die and be relegated to the scrap heap of historical religious curiosity. The only sucessful sects therefore nearly always have at their head a bona fide spiritual master, who leads their respective movement in a way that ensures the best possible modern interpretation of often outdated scriptures and former masters who have come from another time and culture.