The folks over at Performancing have just released a kickass blogging extension for Firefox. If you blog, and you thought you needed some 3rd party browser just to get nice blogging tools in your browser, think again. This extension, even though it's an early version, is all you need :-)
update: Oh, I almost forgot. Need spellchecking? The latest development build of SpellBound integrates seamlessly with this blogging tool.