I noticed that another person posted about Vocabulary and Spelling City, and we use that site. I have another site to mention about vocabulary and grammar. This site (Vocabulary.co.il) has many games that allow your children to practice parts of speech. It is not just for young children either, as there is a review for the SAT test. Of course, it is not as demanding as the SAT but it is a great place for your older child to just do practices that will keep their brains nimble.
There are typing games as well, which will help your child with keyboarding skills.
Any time a review can be fun or a game, I'm all for it. There is no reason why practicing and reviewing need to be totally boring. My daughter loves this site because she gets to "play". I can even use it as a reward because she enjoys it so much. Grammar can be so dry to learn, and this site makes it less tedious.
I will mention, though it probably goes without saying, since I am posting it on this board, but Vocabulary.co.il is free, and you will not be surprised by anything unsavory on that site.
Homeschooling mom of child for almost 5 years and counting!