Cutnell/Johnson: Student Companion Site - The online companion site to the Honors Physics textbook. Contains interactive simulations, practice problems, self tests, and more. http://bcs.wiley.com/he-bcs/Books?action=index&itemId=0471663158&bcsId=3138
Physics Forum - Excellent online bulletin board-based site dedicated to Physics and Math. Post general questions or specific ones and receive answers from teachers/students all over the world. http://www.physicsforums.com/index.php
Physics Classroom - Having trouble with a certain topic? Check out this site's guide to high school physics, including lessons, example problems, and practice problems. http://www.physicsclassroom.com/