Canberra Society of Editors
Australian Society for Technical Communication
ACT Writers Centre
Write Better English: a FREE online community of wordsmiths and word lovers dedicated to improving people's written English skills
Merriam Webster online dictionary, yes it's American English, but their Word of the Day tool is nifty for impressing people
Babel Fish: online language translator
4 Syllables is a website with a lot of excellent articles about web content accessibility.
AccessibilityOz are experts who deal with web content and design for accessibility. Check out their awesome fact sheets.