A handy tip I came across the other day was how to spell-check an entire web page using Firefox – not just textarea elements.
You basically put the page into design mode – so the content becomes editable. Enter this in the URL bar:
You can also add spell checking to fields which do not have it by default (e.g. single-line input elements) by adding a “spellcheck” attribute set to “true”, e.g.:
<input type="text" size="50" spellcheck="true">
See https://developer.mozilla.org/en/Controlling_spell_checking_in_HTML_forms for more information.