Rei - In Japanese the character Rei stands for holy spirit, mystery, gift, nature spirit or invisible spirit.
Ki - this character means energy, nature scene, talent and feeling.
Usually Reiki is translated as universal life energy.
Reiki can be used to heal everything - yourself, others, food, animals and all situations (past, present and future). Reiki can be sent to wars and diseases, plants, trees, polluted rivers, the sick, even to a forthcoming job interview!
Attunements are given to those how seek to practice Reiki (those who take the Reiki degrees as I have done).
Attunements work by opening and expanding the holding capacity of energy channels and clear these channels of energy blockages allowing Reiki energy to flow into the healer.
Reiki is a natural and simple healing method which allows you to absorb more life force energy. The Reiki method vitalises your life force and balances the energies in your body. This natural healing energy flows in a powerful and concentrated form through the hands of the Reiki giver. The laying on of the hands directs this healing energy into the body of the receiver (although healing can be given without touch for example, through the back or under wheelchair or over areas of the body where you may not be familiar enough to touch!) The Reiki giver is used as a channel to conduct the universal life energy. As a result, no personal energy is drawn or drained from the giver, who is simultaneously charged and strengthened.
Reiki history - Dr Mikao Usui lived in the late 1800's. He was president of a Christian university in Kyoto, Japan, and he was a Christian minister. One day a student asked him "Do you accept the contents of the Bible?" The answer was "yes" The student said "In the Bible Jesus cured the sick, he was a healer. Have you ever seen this happen?" Dr Usui agreed he had not and decided we need to see it with our own eyes. He went to the USA University of Chicago and took a Doctorate in scriptures to try to uncover the secret of how to heal.
In Buddhism the Buddha had the power to heal. So he returned to Japan to learn Buddhism and was admitted to a monastery to study Budddhism scriptures (The Sutras). He studied in Japanese, Chinese and Sanskrit ancient languages. He found the formula (the symbols), the description of how Buddha healed. After 7 years he uncovered the knowledge but he didn't have the power. He went to a sacred mountain (Mount Kurama) to meditate. He meditated for 21 days. On day 1 he placed 21 pebbles around him. On the 21st day he became aware of a beam of light from the heavens that came towards him. He was struck by the light and knocked over. He saw bubbles of light, symbols that he had discovered in his studies. The key to healing of Buddha and Jesus.
He walked down the mountain and stubbed his toe. As he held his toe, it healed. At an inn he met a girl who was crying with toothache; he cupped her cheeks in his hands and in minutes the pain had gone. Later that night he healed a friend of arthritis.
For 7 years he worked with beggars but they preferred their old way of life. Begging gave them a sort of living. Dr Usui realised that he had healed the physical body, but not taught appreciation for a new way of living. He left to teach others in the cities and gave the principles of Reiki.
How Reiki came to the western world:
Dr Chujiro Hayashi was a retired naval officer who was initiated by Dr Usui. When Dr Usui's life was drawing to an end Dy Hayashi was made Master of Reiki to keep the essence going. He founded a clinic in Tokyo for treatment and learning. In 1935 a young woman from Hamaii came to Japan for a tumour to be surgically removed. She asked for Reiki instead. Her treatment worked. She stayed and Dr Hayashi trained her for one year. Her name was Mrs Hamayo Takata. She returned to Hawaii and opened a clinic there. In 1938 Mr Takata was initiated as a Master. As the war was about to begin, Hayashi knew he would not fight. Mrs Takata arrived back in Japan to be with Hayashi. He told her many things and as she was Japanese/American it was clear she had to go for her protection and the protection of Reiki. When all his business was settled he called his family and Reiki Masters. Mrs Takata was to be his successor - he died toon after. Mrs Takata died in 1980. Today, the Usui system of natural healing is practised all over the world.
Makao Usui was born on August 15th 1865 (I finished my 21 day cleansing process on 15th August 2003 which I thought was a conincidence - after recieving your first attunements you receive an initial, very powerful healing so powerful changes may occur during this time) and he died on March 9th 1926 of a stroke after recovering from 2 previous ones. He taught Reiki to over 2000 people. There were Reiki centres and clinics in most parts of Japan by the time he died. Dr Usui was a very warm, simple and humble person. He never showed off, he always had a smile on his face. He was very courageous in the face of adversity. He was at the same time a very cautious man. His talents were many. He liked to read and his knowledge of medicine, psychology, fortune telling and the theology of religions around the world was vast. His lifelong habbit of studying and gathering information certainly helped pave the way to preceiving and understanding Reiki.
Reiki not only heals diseases but also amplifies innate abilities, balances the spirit, makes the body healthy and thus helps achiece happiness. The ultimate goal is to understand the ancient sectret method for gaining happiness (Reiki) and thereby discover an all-purpose cure for many ailments.
There is a book called Essential Reiki by Diane Stein which caused up-roar amongst Reiki Masters/givers... the symbols given during attunements, some of which are used during the healing, are secret and are only given and shared by Reiki Masters/healers. Diane Stein has printed them in her book! So, there is room to believe you can give yourself/others the attunements in the privacy of your own home at a cost of 18 pounds and 95 pence instead of the several hundreds of pounds you would pay a Reiki Master! Reiki Masters however believe that attunements can only be given correctly by someone who has had all 3 levels of attunements - in other words, only a Master of Reiki can give these symbols to you. A very money orientated argument maybe?
In my experience both giving and receiving Reiki are wonderful processes and a great deal of money is spent receiving these attunements to be able to be Reiki 'givers' but I think that if your intention is there, anyone can channel and direct universal energy.
puredawn
Pro 
It's been the money involved in Reiki that I've been uncomfortable with; as you know, my belief is in line with your closing remark. It is all about the intention.