I experimented with quite a few off-line blogging tools before I decided that ecto was a good choice. When you select a tool like this It is hard to know if the maintainer will continue to upgrade and improve it. I have been using ecto about six months and think I have had a least two updates during this time which is good.
To use any off-line blogging tool with Drupal you need to enable the Blog API. This can be found on the modules page, in the Core-optional section. If you're using ecto and it is the latest version then Drupal it's available in the list when you click in new account. In actual fact the software uses the settings for the movable type blog which must use the same blogger API, so worst-case select movable type as your blog type.
Once you've enabled the Blog API on Drupal you will need to edit the options in the site configurations menu. If you have any cck content types available you can also publish directly to these, however, you will not be able to populate any CCK fields, only the title and body fields. This can still be useful in my opinion even though you may need to log in and add additional parts to the post after you published it. This may include images, files or anything similar, such as taxonomy. You will need to give this URL to ecto http://www.yoursite.com/xmlrpc.php
Ecto makes a lot of things easier but sometimes the markup isn't great. For example, if your inserting image in line using ecto, and you want to right align it it places a div around the image which often makes it impossible to wrap the text attractively. Outside of this issue it does work very well and has some nifty features.
One of these features is that when you want to add a hyperlink and you have already copied a link to your clipboard when you click the link button it pre-populates the link field automatically. Additionally, it remembers this information, so if you go to hyperlink other words with the same URL it remembers the title and window properties of the link.
If you like a little bit of affiliate stuff with Amazon, it has an Amazon product chooser. This links you directly in with Amazon's catalogue. For those of you who like to blog when you travel, or reference images on Flickr, you can do this directly from within ecto.
You're also able to import media from your own machine. I use a Mac, so I'm able to import media from iPhoto, iMovie and iTunes, which can be handy.
It there will download any existing blog entries that you have on your site. It can pull down your existing taxonomy terms, but for some reason I don't always have 100% success with free tagging.
Overall, this is a great product if you do a lot of blogging, or manage a lot of blogs as you are free from wait times of page loads and you have the option to save regularly to your local machine without the fear of losing all of your post. If one day it is able to cope with CCK fields this would put the icing on the cake and there is no doubt in my mind that many Drupal users would adopt that, but this is a bigger ask.
Ecto is one of many off-line blogging tools and are available. I chose it because it is so Mac friendly and it just works.
The developer also develops other software such as the Flickr 1001 app, although I can't see this on his site.
ecto supports blogger, WordPress, nucleus, Drupal, squarespace, movable type, Typepad and many others.
PS- this post was written using ecto.