I have been searching for a good blog-editor for MacOS and experimented with a number of them (Sadly there are not many available). Most of the professional bloggers on MacOS use either Ecto or MarsEdit and while these are decent options, these are not free and I would not say the best options for amateurs bloggers for two reasons. One, they are still have some bugs, and second, they are not free. There is another option Qumana, which is available all the platforms, but I find it rather slow and buggy.
Finally I settled down to Scribefire, a very powerful browser extension that is available for Firefox, Opera and Chrome and available for all platforms. It offeres all the features of a normal desktop blog-editor and very light on resources. It supports all the major blogging platforms (Blogger, WordPress, Liverjournal) and if you are using any of the free blogging platforms the installation is breeze. You just need to fill in the blog url and it automatically detects the settings.
Though configuring self-hosted blogs is a bit problematic. I did not detect the settings for my this (http://santoshsing.net) wordpress blog automatically and I had to provide the settings manually. But it is not that difficult. Here is how you can easily configure it.
1. First, login to your blog admin (htttp://blogurl/wp-admin)
2. Go to Dashboard–>Setting–>Writing and enable remote publising xml-rpc (tick it on if it is not already ticked)
3. Now install the ScribeFire extension in your browser, open it and click on Add a new blog.
4. Fill in the blog url, Select blogtype -Wordpress, and put your api url (http://yourblogurl/xml-rpc/php)
5. Provide your blog admin username and password.
You are all set to blog now.