Wikimedia
Wikipedia: Pythagoras
Encyclopedia article about Pythagoras that looks at his life, accomplishments, and his influence on other mathematicians. Includes pictures and links to additional information.
University of St. Andrews (UK)
University of St. Andrews: Pythagoras of Samos
Provides much information on the life of Pythagoras of Samos.
Other
Thebigview.com: Pythagoras
Easy to read biography of Pythagoras that discusses his life, work, and questions raised by his ideas. Includes some interesting stories about some of his personal beliefs.