Online English Activities for Kids - great fun!
Wordcentral - excellent word games and codes!
Rhyming Dictionary - perfect poetry - check it out
Websters Dictionary - fast and accurate resource.
Wordsmyth English Dictionary - superb
Roget's Online Thesaurus - massive database of words

Some useful and fun Internet links:

200+ Proverbs - loads to learn here.
National Year of reading & Authors Online - try their challenges.
Guess the word - ace word definition game.
Online Picture Dictionary - letters, pictures & Internet links - great!
Online Books Database - read hundreds of books on the Internet.

Authors and Publishers Online:

Paul Jennings - Australian childrens author
Andy Griffiths - Australian childrens author
Michael Salmon - Australian childrens author and Illustrator.
"Dr Seuss" - popular site with many games and activities.
"Treasure Island" - read the story online - with activities!
Puffin Books - reviews and info.