If you use flashcards, then here is a site that let's you easily find, create, share and study flashcard for any subject. A useful test prep tool.
explains all the key people, events, particles, vocabulary and theories that chemistry has been built on - very useful site to use as a reference for most concepts we cover
introduction and helpful practice with using deminsional analysis
How we utilize isotopes in daily practice
encyclopedia of science terms, ideas, people... anything science related