Bunch of sites with practice problems:
http://www.examswithsolutions.com/Subjects/statistics.html
https://www.varsitytutors.com/ap_statistics-practice-tests
http://stattrek.com/statistics/problems.aspx
Exam Tips:
http://apstatsmonkey.com/StatsMonkey/AP_Review_files/APStudyHints.pdf
http://stattrek.com/tutorials/ap-statistics-tutorial.aspx
