This site has an excellent selection of over 900 free AP Chemistry mutiple choice questions. They are organized by unit so that you can review them all or just focus by topic.

This is a huge collection of practice quizzes including chapter review questions and many tests on many specific topics. This is an amazing resource, fully updated for the new test.

A complete midterm test with AP Chemistry multiple choice and free response. Lots of challenging questions in a PDF file. Video solutions are here.

Crack AP offers over 50 multiple choice practice tests for AP Chemistry. There are also specific topic tests for each unit. At the end of each test there is an answer key and explanations.

Khan Academy has a great selection of practice questions for all units covered on the exam, as well as videos and other resources to help your studying.

In this hour and a half long video, Mr. DeWitt explains how to solve a variety of AP Chemistry practice problems. Try to test yourself first before watching the video explanation!