You can post to Tumblr right from iA Writer using a simple AppleScript; all you need is your private email publishing address from Tumblr – click here for instructions on how to set this up.
Once you have this address, open up the AppleScript Editor on your Mac, create a new document, and paste in the following AppleScript:
The only thing you need to change is the line:
set tumblr_email to "YOUREMAILPUBLISHINGCODE@tumblr.com"
You should change
YOUREMAILPUBLISHINGCODE@tumblr.com to the email address provided to you by Tumblr.
Save the AppleScript to wherever you like.
Now, create a new iA Writer document, type in and save a sample blog post and then run the AppleScript we just made (either from the editor or from something like FastScripts). A Mail window will pop up with your post. Hit send, and a minute later you should see a new post appear on your Tumblr blog.
Another option is to set up a Print Automation from iA Writer, but I found this to be a little too cantankerous.
If you have trouble or my instructions weren’t clear, feel free to contact me on Twitter.