Ecto is my favorite blogging editor for the Mac. The WYSIWYG (what you see is what you get) editor is so powerful it sends my blogging productivity through the roof.
Generally I don’t like WYSIWYG editors because they produce nasty HTML. Not Ecto. It creates some of the most beautiful code I’ve ever seen a computer generate (thinking Frontpage).
Even if you enter malformed HTML, Ecto is smart enough to correct it for you. It’s not always perfect, but it does an amazing job.
One thing I’ve been missing from Ecto is the ability to create headlines using the toolbar. A quick look in custom tags (in the toolbar) revealed an extremely powerful way to do this.

From the dialog you can see Custom Tags is extremely customizable. Not only can you specify HTML tags, but also CSS styles and HTML attributes. This opens up the possibility to save any tag you use frequently directly to the toolbar.
You can also set a shortcut for a tag by clicking “Set shortcut” and pressing the keys for your shortcut. Be sure not to use one already taken by the application. For example, Command+H is already used to hide a window, so this wouldn’t be a good shortcut.

Finally you can set a custom button to use in the toolbar by clicking the icon next to “Button text” and double clicking the icon you wish to use.

This adds an icon onto the end of your toolbar.
Before:

After:

Another popular blogging editor is MarsEdit which you may be interested in. It’s also very customizable, but doesn’t have as powerful WYSIWYG as Ecto.
