Other
Aish.com: What Is a Rabbi?
Aish.com answers the title question, describes how a rabbi differs from clergymen in other religions, and briefly describes how a Jewish person becomes a rabbi.
Judaism 101
Judaism 101: Rabbis, Priests & Other Religious Functions
This site provides a basic overview of the functions performed by a rabbi, chazzan, gabai, kohein, levi, rebbe, and tzaddik. The overviews are thoughtful and convey the information in an easy to read format.