eMedicine Health - Hives and Angioedema -
 Consumer health resource center providing information on the causes, symptoms, and treatment.
http://www.emedicinehealth.com/articles/8611-1.asp

Hives - DrGreene.com -
 Question and answer format explaining possible causes of hives, as well as treatment and prevention.
http://www.drgreene.org/

Hives - DrGreene.com -
Read an article explaining a common rash and its many causes.
http://www.drgreene.com/21_1117.html

International Chronic Urticaria Society -
 Extensive clinical and anecdotal information about chronic hives from members of a mailing list support group.
http://www.urticaria.thunderworksinc.com

Stop And Smell The Roses -
 Living with Urticaria Pigmentosa. Find articles and information about a book.
http://www.angelfire.com/weird2/ripleystvguest/

Understanding Urticaria -
A flash presentation showing the causes and treatment of urticaria. It also illustrates how steroids suppress urticaria without helping.
http://www.urticaria.com/flaUrt/urticaria.html

Urticaria hub -
 A brief definition of urticaria, followed by links to overviews, research articles, case reports and images
http://www.healthubs.com/urticaria

Urticaria Pigmentosa -
Causes, prognosis and treatment.
http://www.capederm.com/info_urticaria_pigmentosa.htm