- ScribeFire Firefox extension - officially not exactly a desktop client as it works inside of Firefox (I use this and I find it very easy to use)
- Windows Live Writer - a great tool and part of the growing Windows Office Live offering
- ecto for MacOSX and Windows - created for Mac users and still the king
Basically, these tools let you blog directly from your desktop without logging in to your blog. I like using ScribeFire because I can click on an icon and it opens up a window on the bottom half of my screen. This allows me to see what I am blogging about in the top half (see below):
Powered by ScribeFire.