MarsEdit - MarsEdit is a desktop blog editing application for the Mac. It provides an offline interface to most popular blogging systems. WordPress, Blogger, Tumblr, Movable Type, and many other systems are supported.
Desk - An award-winning & beloved desktop publishing client, exclusively for OS X.
Open Live Writer - Open Live Writer makes it easy to write, preview, and post to your blog.
BlogDesk - Blogging should be simple, but it gets complicated and time-consuming if you are serious about it.
Blogo - The easiest & fastest way to write, publish & manage blogs