Study Edge Statistics: Open to teachers, students and parents. Video lessons of statistics topics.
OpenStax from Rice University: Free PDF version of Introductory Statistics Textbook.
Kahn Academy: Statistics and Probability lessons. They are working on additional material for the AP test but that won't be released for awhile.
DanShuster.com: AP Statistics teacher in Texas who has developed a lot of statistics resources over the years he has taught the course.
Locus: Statistics questions with answers and explanations.