ecto (all lower case, Mac and Windows versions available) is a stand-alone blogging program that works with all the major blogging systems, including WordPress (hosted and self-hosted), TypePad, and Blogger. It is like having a word processor for your blog. It allows you to work offline and then upload your posts when they are ready—or even schedule them for posting later.
The program allows for extreme customization. It has a WYSIWIG mode, but I work in HTML mode. I have created all kinds of custom tags that save me lots of time. You can even manage custom fields in WordPress. It has syntax highlighting and the ability to validate your HTML. (If you don’t have any idea what I have said in this paragraph, this program is probably not for you.)
If you are a power user, then you definitely should check out this program. I could not blog effectively without it.