I like the Performancing extension - it lets you create and post a blog post from every page on the Web. You give them your blog host password, and it takes care of the rest.
Couple of problems though - when you post a blog post, the default is as "draft" status, at least with Blogger. In order to make the post go live on the blog, you have to go to the blog host anyway to change it from draft to live status, so the time-saving evaporates.
Also, it would be neat if they integrated a way for me to tag my posts.
