http://www.funbrain.com/funbrain/spellroo/

http://www.spelling.hemscott.net/

http://www.everydayspelling.com/

And here are some spelling strategies you can try...

Strategies	How to Use Them
Steps for Spelling New Words	1. Look at the word and say it. 2. Spell it aloud. 3. Think about it. 4. Picture it. 5. Look at it and write it. 6. Cover, write, and check it.
Rhyming Helpers	Link a word with a rhyming word that is spelled the same at the end: unless mess
Problem Parts	Identify the part of the word that gives you problems and study it extra hard: wrong laughed
Creating Memory Tricks	Link tricky words with a memory helper that has the same problem letters: Tell that mosquito to quit biting me.
Using Meaning Helpers	Pair a word with a shorter, related word that gives a sound clue: act--action hea--health
Divide and Conquer	Divide a word into smaller parts: team/mate beauti/ful ar/ti/fi/cial
Pronouncing for Spelling	Pronounce a word correctly: pro/ba/bly Or make up a secret pronunciation: choc/o/late