This website is a self-paced review of concepts for gen chem and includes test questions (and answers) for the reader. It would be a great site to point your intro chem students to if they want/need extra review. It is a set of 10 units, covering things like stoichiometry, unit conversions, and basic acid-base chemistry.
A student should be able to review most of the basic concepts of general/inorganic chemistry after using this website.
This site came highly recommended to me at a recent conference, though I have not used it in my teaching.