Judaism 101
Judaism 101: Bar Mitzvah, Bat Mitzvah and Confirmation
This site does a nice job in explaining how the Bar & Bat Mitzvah have evolved. It also contains information on Jewish Confirmation, and includes many links to related topics.
Other
Ahavat Israel: Yom Kippur :The Day of Atonement
Defines Yom Kippur. Discusses kaparot, atonement, treatment of food and clothing.
American-Israeli Cooperative Enterprise
Jewish Virtual Library: Glossary of Jewish Terms
Basic definition of abelut. Reference to shiva as well. A large glossary of definitions for the Jewish Student.