Cluster Headache Help - Provides links to health, research, government, news, and personal sites related to living with this ailment. Some of the information is dated, but this is still a good resource. - http://www.chhelp.org/index.html
FamilyDoctor.org - Cluster Headaches - Information about cluster headaches from the American Academy of Family Physicians. - http://familydoctor.org/online/famdocen/home/common/brain/disorders/035.html
eMedicine - Cluster Headache - Highly technical discussion of causes and treatments for health care professionals. - http://www.emedicine.com/EMERG/topic229.htm
Wikipedia - Cluster Headache - Excellent resource with detailed information about symptoms and treatments. - http://en.wikipedia.org/wiki/Cluster_headache
Organization for Understanding Cluster Headaches - Information about OUCH and its activities. Includes a quiz, medical information, comparison table and the International Headache Society diagnostic criteria. - http://www.ouch-us.org/index.shtml
OUCH (UK) - Charity and expert patient group dedicated to helping cluster headache sufferers in the UK. Find support and membership details. - http://www.ouchuk.org
Cluster Headache - Consumer health resource center providing information on the causes, symptoms, and treatment. From eMedicine Health. - http://www.emedicinehealth.com/articles/9362-1.asp
eMedicine Health - Cluster Headache FAQs - Consumer health resource with FAQs relating to these headaches characterized by short-lived attacks of sudden, severe pain around one of the eyes. - http://www.emedicinehealth.com/articles/37974-1.asp
Cluster Busters - International organization dedicated to researching and promoting the treatment of cluster headaches with hallucinogenic substances. - http://www.clusterbusters.com
A ClusterHead's Life - Weblog by a Canadian sufferer. - http://versilleus.blogspot.com