Homeschool Enrichment Magazine the Nov/Dec 2010 edition titled "Blogging to Teach Writing" by Gail Heaton, which discussed the infamous assignment of handing students a blank piece of paper and having them write what they "Did for the Summer" in 500 words. Why not consider letting your student begin a blog?
Your child's blog could be a journal of sorts, a way to get out his feelings- or it could be dedicated to a specific topic or theme. If sports interest your child, let him write about his favorite hero or team and give commentary on the game. If animals interest your child, let her record her observations of a bird feeder or a trip to the zoo.
Of course there are security issues to consider. Will the blog be public or private? Will you allow photos of your children and their friends on the blog? Will you allow commentary from other people? All these things will depend upon the age of your child, and their development.