http://www.funbrain.com/ A site for online educational games (math, grammar, science, spelling, history) recommended for students 3rd grade and younger. Has a very strong push to buy a membership. The free games are worth the visit however.
Style Guidelines & Grammar:
http://owl.english.purdue.edu/ Need to check writing standards for either MLA or APA style? This is my go to site. A wonderful resource for all ages.