Marco Arment, the lead developer of Tumblr, the popular microblogging community, released an app for Mac to backup Tumblr blog called the Tumblr Backup app.
It is a simple backup tool but unlike the traditional approach, the blog’s content after backup can be viewed on any computer, burned to a CD/DVD, or hosted as an archive of HTML file.
If you have a Tumblr blog, you might want to give it a shot. The app is in public beta and there are few limitations, such as, the output is saved in plain theme, photosets are not fully downloaded, etc. Hopefully the developer plans to implement these functionalities in the final release. Hit the link below to see the full release notes.
Works on Mac OS X 10.5 and higher. Enjoy!