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.
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.
Wolfram Research
Wolfram Science World: Pythagoras of Samos (Ca. 560 Ca. 480 Bc)
This site from ScienceWorld provides a short, informative description of many of the contributions of Pythagoras to mathematics. Links exist to some of the contributions as well as to additional information.
Instituto Latinoamericano de la Comunicacion Educativa
Red Escolar: Mathemata
Learn a little history of Pythagoras of Samos and the relationship between numbers and their divisors.