I recently purchased MarsEdit for Mac OS since I wanted to be able to write blog posts for some of my WordPress and Drupal sites via a desktop application. This is great if you like to write posts while you don’t have an internet connection, or if you are writing some long stories and need to work on the draft for a while.
Integration with WordPress and Drupal sites are seamless and I have not experienced any problems thus far (only been using it a few days, but still). It supports tagging, categorizing, setting post status, comment settings, enabling trackbacks, markup and much more! Not too shabby for $29.95.
Check out the developer’s site here for more info: Red Sweater Software – MarsEdit