Online sites for home study:

Online groups for kids
The Stacks (ages 8-12)
Includes blog posts, games, videos and a message board. The blog includes a category called "writing prompts" to give you simple writing tasks for the comments.
Family Playground (ages 3-7)
Games and stories based on popular book series (I Spy, Magic School Bus, Clifford, etc.)
National Geographic Kids
Discovery Kids
National Wildlife Foundation Kids (includes a link to story and game apps, too)
San Diego Zoo Kids
The Exploratorium

Reading

Meegenius (free books for listening and reading)
Storyline Online (stories read by actors)
Tarheel Readers (easy stories on many topics)
National Geographic Kids (reading about animals and other topics)

Phonics
Literactive
Starfall
Oxford Owl

Spelling
Kids Spell (Select a spelling list and play games to practice the words)

Writing
Fun Brain (Word Games)
Book Report Sandwich Station (how to write a book report)
Xtranormal (movie maker)
ToonDoo (comic maker)

Listening
English Central (listening and pronunciation with videos)
Most Shocking World Cup Moments (12 part documentary--each part is about 10 minutes)

More
zui.com (safe site with videos and games)
Brain Pop ESL (animated English lessons--click on Free Lessons)
Brain Pop (learning about school subjects in English)
Brain Pop Jr (same as Brain Pop but for kindergarten through 3rd grade)

Blogs
Ririko's blog
Satoshi's blog
Pomhi's blog