http://www.abcya.com This is a great site for grades K-5. I often recommend that this is a good place to start for practicing literacy skills in a game like setting at home. Students seem to really enjoy this site.
http://starfall.com This is another site that is free online and I feel is very good. It is a site I would recommend for grades K-3 depending on your learners. It is a solid reading program using phonics to build reading skills.
http://tumblebooks.com Wow I love these online books! You can find them by searching through google: tumblebooks Vancouver Island Regional Library. I believe that most public libraries offer these readers for free. They are talking books that have added animation, sounds, and music. TumbleBooks come in three levels: TumbleBookLibrary which are picture books for kids, TumbleBookCloud Junior (over 600 titles) for grades 3-8, and TumbleBookCloud (600 titles) for middle and high school readers. TumbleBookCloud Junior has a selection of early chapter books, graphic novels and National Geographic videos. TumbleBookCloud offers novels, poems, classics, and graphic novels. This is another great resource for families to have at home. All they need to do is to sign up for a public library card.