Blog.gears is an offline Blogger client which allows users to write posts offline. This is very useful feature if you don’t have net connection all the time.

In order to use this feature you need to install Google Gears first. If you have Google gears go to Blog.gears and click on the link login, it will ask you to grant access to blogger. Once you permit it to access it you can start posting new posts or edit the older posts. If you are connected to the internet you can immediately publish the posts. See the screenshots to see how it works. (I have created a dummy blog to test these features.)

Google Gears supports Google reader and now they have added support for blogger, next may be gmail

Via Google Gears API Blog