This is a little late, but thought it was worth sharing… Google just released a Toolbar for Mozilla Firefox. I probably won’t be installing it, but you might find it useful. Here are some of the features:

• SpellCheck
  Check your spelling whenever you type in web forms
• AutoLink (US only)
  Turn street addresses into links to online maps
• AutoFill
  Automatically fill out forms for faster online shopping
• WordTranslator
  Translate English words into other languages