Very Brief lists of different forms of Reiki

Types of Reiki

Usui Reiki: Mikao Usui was the founder of reiki, which is practiced all over the world. Hawayo Takata, a Japanese woman, spread the teachings of Reiki, to the West.

Tibetan Reiki: This form of reiki is a powerful Tibetan method of attunement and combines certain techniques from the original Usui reiki.

Karuna Reiki: Karuna means a profound feeling to alleviate suffering, with abiding compassion towards all beings. Karuna Reiki employs sounds, endowed with the power to heal. These sounds are sacred and powerful. They can be transmitted silently through intention or chanting, to bring about deeper levels of healing. The power of Karuna Reiki is used to heal addictions.

Gendai Reiki: Gendai means modern. Mr. Hiroshi Doi is the founder of this reiki. He brings a strong Buddhist perspective to the original reiki teachings.

Rainbow Reiki: Walter Lubeck, a reiki master began this form of reiki. In this system, working with the seven main chakras in the body brings about healing. These chakras organize a body of light. This spiritual energy is used to heal and understand our true nature.

Five Element Seichem: Alex Baisley in Canada founded this system. This helps us to consciously use the five elements of the universal life force or prana to promote healing. Also, Tera Mai Seichem, which I work with is a combination of Reiki (earth), Sakara (fire), Sophi'El (water) and Angeliclight (air and spirit) and was founded by Kathleen Milner. It sounds very similar to Alex Baisley's variation but I have never experienced his to say for sure

Shamballa Reiki: This system helps to cleanse, repair and balance the physical, emotional, mental and spiritual levels of a person. It uses reiki energy along with many vibratory symbols and healing rays to achieve the purpose.

Kundalini Reiki: In this system, reiki energy is channeled through the lower base chakra rather than crown chakra. This kindles spirituality and even helps the practitioner get over shyness, or recover from trauma and other negative emotions.

Imara Reiki: The reiki energy is used to work on past life, repressed issues and helps in long distance healing. The practitioner is connected to ascended masters and angels.

Others Include
Angelic Reiki
Archangelic Reiki
Brahma Satya Reiki
Celtic Reiki
Christian Reiki
Crystal Reiki
Divine Light Reiki
Dragon Reiki
Fire Serpent Reiki
Gayatri Reiki
Heart Reiki
Huna Reiki
Inga Reiki
Inner Light Reiki
Karuna Reiki
Komyo Reiki
Kundalini Reiki
Laxmi Reiki
Lightarian Reiki
Lotus Petal Reiki
Maori Reiki
Purple Reiki
Pyramid Reiki
Reiki Brenham
Reiki Crystal Healing
Sacred Moon Reiki
Seichim Reiki
Shamanic Reiki
SKHM Reiki (original Egyptian Seichem from Patrick Zygler)
Tera Mai Reiki
Tummo Reiki
Usui Reiki Ryoho
Vajra Tummo Reiki
Violet Flame Reiki
White Dove Reiki
White Light Reiki

The above lists were taken from
http://www.reikipages.com/reiki-types/
http://www.medindia.net/alternativemedicine/Reiki/reiki7.htm

this is very interesting! i never knew there were so many variations of Reiki!!!!!! woooo!!!!!!