John Forsythe has a nice list of a number of Offline Blogging packages that work directly with DasBlog via the Blogger or MetaWebLog API.
Here's the ones he got working:
Personally, I use (and can't say enough nice things about) BlogJet for ALL my posts. It's fantastically easy to get working with DasBlog as has a pre-configured setting for DasBlog. It supports pre- and post-dating of posts, categories, has fantastic imaging support and automatic thumbnail generation. It also supports Music Detection (adding what you're listening to to the bottom of the post) along with Voice Attachments (a recorder is included) and overcomes the Blogger/Metaweblog APIs lack of support for attachments by using a parallel FTP upload. Very slick.
Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. I am a failed stand-up comic, a cornrower, and a book author.
Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.