PhET Colorado Simulations is aimed towards college-level and high school chemistry students and includes interactive simulations on many different chemistry topics.
Brightstorm has online chemistry video lessons to help students understand critical chemistry concepts so they can improve test and quiz scores and more easily complete homework assignments.
Khan Academy has many example videos of problems in chemistry. This is a great tool to brush up on your understanding of chemistry topics.
Periodic Table of Videos has a short video for each element in the period table showing stories, samples, and experiments.
Jefferson Lab has a collection of fun experiments on video as well as games and homework help.
The ChemTeam provides study resources in all topics of chemistry for high school and AP chemistry including tutorials, videos, and problem sets.
Regents Exam Prep has reviews, study-aids and problem sets in various chemistry topics.