One of my favorite apps on Windows is Windows Live Writer. It is a 'what-you-see-is-what-you-get' (a.k.a. WYSIWYG) blog editor for Windows and integrates well with Wordpress, Blogger, and other blogging services. However, Live Writer is not available for Mac OS X and I don't have the cash to pay for a similar app on the Mac App Store. But I did find something comparable and incredibly usable, ScribeFire.
ScribeFire is a "web app" for Mozilla Firefox or Google Chrome. Essentially, it is a browser plug-in and it is completely free! I use Google Chrome is my primary web browser both at work and at home. I added ScribeFire to my Chrome browser from the Chrome Marketplace and the plug-in settings synced with my Google account. Now, anytime I want to post something to my blog, I can do it from any of my computers with Google Chrome!
ScribeFire has some excellent features such as Post Templates, Tagging, import audio and video from YouTube, picture injection, and Zemanta integration. If you have Google Chrome or Mozilla Firefox, it is worth checking out since it is free. http://www.scribefire.com