I use an app called MarsEdit to author my blog posts. I really like it and I recommend anyone using a Mac to check it out. Great piece of indie developed software that just works.
Something cool that it enables is the ability to preview your post in the style of your blog. The template that comes with the app isn’t bad but of course it likely doesn’t match your site. In the past I’ve gone into the web inspector in Safari and took the html for my site and put it into the preview template.
I just learned however that MarsEdit has the ability to download a preview template from your website. I clicked the button and ~10 seconds later I have a preview of my site that just works. What an amazing feature. I don’t know if it’s new or not, but really appreciate the coolness factor.