Blogging With The Full-featured Blog Editor - ScribeFire

ScribeFire is one of the most popular add-ons for firefox. Actually, it is not only for firefox, you can also find the add-on for chrome & safari. Since it's an add-on, you could use it cross platform.

ScribeFire is a full-featured blog editor that integrates with your browser and lets you easily post to all of your blogs. You can post to blogs from WordPress, Blogger, TypePad, Windows Live Spaces or any other blog that supports the MetaWeblog or MovableType APIs.

You can edit the existing posts. It's editor is more powerful than blogger, you can bookmark your posts easily to del.icio.us, set pings for posts after you post them, and ScribeFire is partnered with Inlinks.com, you could find a easy way to monetize. My favorite feature is you could schedule posts for the future, then it'll post articles automatically, it's really nice for blogger.