For essential oils see this post.
Quantum Touch is an energy-based modality that works to heal.
Reiki Really Works: A Groundbreaking Scientific Study
Free Reiki Course Certified Practitioner Level 1 Full Video
Gemmotherapy is a treatment for detoxification that uses extracts taken from young plants and plant buds. It is unclear to me if this is a form of homeopathy or more of an herbal supplement.
Gerson Therapy is primarily a food-based therapeutic approach which uses a lot of juicing of fruits and vegetables. It is most commonly used for cancer but has been used (supposedly successfully) for many other health conditions as well.
Grounding (aka "Earthing") The basic idea here is that the earth is a source of spare electrons and that if we touch the earth either with bare skin or with a conductive material (such as leather) we can absorb the free electrons which then act as antioxidants to protect our cells and reduce inflammation. As inflammation seems to be at the root of many diseases and conditions, this has the potential to help a wide variety of health problems.
Down To Earth documentary - The Science of Grounding
The basics of homeopathy are explained here on the site for John Melnychuk, a homeopathic doctor that my family has seen and really liked. He specializes in treating autism and related conditions. For a more comprehensive description of the history of homeopathy click here.
The National Center for Homeopathy has a lot of general information about how to use homeopathy and the theory behind it, as well as a database that helps you find a remedy based on a person's symptoms. They also have other membership-based resources.
Interhomeopathy is a site with many resources including case studies, a list of where to get remedies, journal articles, and more.
The HomeopathyPlus site has a database of remedies so you can look up what each one does.
The Homeopathy Research Institute is working to understand the mechanism by which homeopathic medicines work, including looking at some new research into water and its structure that seems related. I've come across this potential explanation and it is very intriguing. They are also researching the effectiveness of homeopathy in treating some specific conditions. A listing of their published research can be found here.
I have another post here that gives information for specific remedies and conditions treated.
The best studies show individualised homeopathic treatment has beneficial effects beyond placebo
Homeopathy is effective according to Swiss federal report
Homeopathic remedies for radiation and radiological procedures (such as x-rays, CT scans)
Treatment of acute childhood diarrhea with homeopathic medicine: a randomized clinical trial in Nicaragua.
Pediatrics. 1994 May;93(5):719-25.
"The statistically significant decrease in the duration of diarrhea in the treatment group suggests that homeopathic treatment might be useful in acute childhood diarrhea. Further study of this treatment deserves consideration."
Fire on the Mountain - A Gathering of Shamans
Soul Retrieval: Trauma, Soul Loss, and Recovery
Ancient Secrets of a Master Healer: Deeper Healing Solutions | Dr Clint Rogers | TEDxWilmington
Healthcare's growing uses for virtual reality (this seems especially promising for treating pain)