MarsEdit is a blog editor for OS X that makes editing your blog like writing email, with spell-checking, drafts, multiple windows, and even AppleScript support.
It works with with most blog services including WordPress, Blogger, Drupal, Movable Type, TypePad, and many others.
Fix a failure to auto-configure some Tumblr-based blogs
Fix a problem that prevented bolds, italics, etc., from being set as default preview fonts
Fix a problem where Typewriter Mode in Rich-Text mode could scroll awkwardly while typing
Restore support for selecting “main category” on Movable Type blogs
Improve indexing and searchability of built-in Help