SpellBound

http://spellbound.sourceforge.net/

SpellBound is a port of the spellchecker code and user interface from the Mozilla Suite's Composer that enables spell checking in web forms such as html textarea / input elements (html input password elements are not checked by SpellBound) and rich text form elements. This allows you to spell check forms (e.g. message board posts, blog entries, wysiwyg, etc.) before submitting them when using your Mozilla Firefox or Mozilla Suite browser.