I am looking for an application (not a browser extension) that supports offline blogging and uploading (when needed). Is there any such tool ?
I am primarily looking for compatibility with Blogger.
Thingamablog is an easy to use and powerful cross platform blogging tool. And when I say "easy to use" I am serious. It can be used to create localhost blogs or put them on your web server with ease. It is as powerful as wordpress, blogger, and it allow you to customize your themes with ease using html.
Unfortunately there is no more official support nor new releases but I can confirm that you can run it in at least 12.04 and probably further.
My current blog and the official Thingamablog website are yet made in Thingamablog. My blog (for demo purposes) can be reached clicking here.
A screenshot of thingamablog working in my 12.04 LTS is placed here. Additional information can be reached in the official website at http://www.thingamablog.com/
Blosxom and Pyblosxom are blogging tools that feed off a plain text file - so very unix. Minimalist and elegant, they also resolve the offline problem.
Alas, not Blogger. But still worth checking out if you want a simple offline way to blog, and vi (or emacs) is your editor of choice.
one of the blogging clients I have used (in GNOME) is Drivel. Though it hasn't been worked on for quite some time (2009). It still worked for me in Ubuntu 12.04. I used it for my blogger and according to its homepage it supports LiveJournal, Blogger, MovableType, Advogato, and Atom journals (systems based off these are also supported, including WordPress and Drupal). Here's a quick overview of its features (also from their website):
It's not super extensive, but for most general blogging without a too fancy lay out it will be just fine. It gets out of your way and provides you with either simple formatting options or you can use raw HTML to format your blogposts.
Hope this helps.