• National Library of Medicine Medline Plus
• EurekAlert
• WebMD

• The Mayo Clinic (highly recommended)
• National Library of Medicine Medline Plus (drugs, health topics...)
• National Institutes of Health (authoritative documents and info)
• Health Finder (various USA government publications)
• Merck Manual of Medical Information -- Home Edition
  (intended for the general public)
• Merck Manual (intended for health professionals)
• Merck Manual in Italian (Manuali Merck)
• UpToDate (especially useful regarding procedures and treatments)
• University of Maryland Medical Center (health topics)
• WebMD

Resources for patients with uncommon diseases:

• NIH Office of Rare Diseases
• National Organization for Rare Disorders

• Alcoholics Anonymous
• Alcoholics Anonymous Europe, Rome page ; AA Rome site
• American Academy of Orthopedic Surgeons: information/brochures on topics from bunions to joint replacement (also en espanol)
• Diabetes and its treatment: American Diabetes Association
• High cholesterol: concepts and treatment
  • WebMD
  • National Institutes of Health
• Spousal abuse (very useful essay and links, from the Mayo Clinic)
• Survivors of sexual violence: Pandora's Acquarium
• Travel information:

  • Centers for Disease Control (authoritative and up-to-date)
  • MD Travel Health (also useful)
• Healthy eating: Dietary Guidelines for Americans 2005
• Irritable bowel syndrome:
  • IBS self-help and support group
• Jackson Gastroenterology (excellent material on various digestive conditions, procedures, etc.)
• Migraine: The Migraine Action Association (self-help group)
• Mental health:  yet another excellent offering from the Mayo Clinic
• Diets for various conditions at Jackson Gastroenterology
• Weight Watchers
• A proposed diet for hypertension:  the DASH Eating Plan
• Dealing with grief, death, and major loss: GriefNet.org
• Menopause
  • Mayo Clinic Women's Health Center
• Postmenopausal hormone therapy
• Sexual issues - Our Bodies Our Selves
• Stress and its effects on health: The End of Stress As We Know It
• X-rays: good information on imaging studies
• Colonoscopy