Shodor Education Foundation
Shodor Interactivate: Probability and Outcome Discussion
This site is a virtual discussion between a teacher and student about probability and outcome. The virtual teacher poses wonderful questions for the students to think about. The virtual students then respond to the inquiries.
Khan Academy
Khan Academy: Probability: The Basics
Provides an introduction to probability. Includes examples, two videos, and links to additional resources, e.g., exercises to try. There are also problems and discussions of them in the Comments section.
Yale University
Yale New Haven Teachers Institute: Introduction to Mathematical Probability
This site gives an overview of probability, including example problems and a reading list. Exhaustive and detailed, this should help dramatically with students looking to study probability.