For those who always type but not write, typing text without spell checking is really painful. Most editors support spell checking. Some web applications like Gmail also support that. There are lots of text input areas on web pages needing this feature. For Firefox, you can use SpellBound. The old versions of SpellBound can be found at http://spellbound.sourceforge.net. You can read this post at MozillaZine for the development version for Firefox 1.5.0. For IE, you may look at ieSpell.