Ok, this really issnt orginal but is based on and a slight improvement on the work of Broken and m0n5t3r.
It allows you to have contents spell checked somewhat alike the way gmail does.
You can download it here http://www.lab4games.net/zz85/blog/wp-content/zz85-plugins/ajax-spell-checker-0.4.zip
Just extract, activate and run.
Hope to hear from you. ")