Performancing for Firefox is a full featured blog editor that resides in your Firefox browser and lets you post directly to your blog while surfing. You can drag and drop formatted text from any web page you are browsing, take notes, and post without going to your blog's admin panel.
Once installed, hit "F8" or click the little pencil icon at the bottom right of your browser window to bring up the blog editor. You can set it up to post directly to your WordPress, MovableType or Blogger blogs.
Performancing is a handy little tool for those that manage multiple blogs and post frequently.