Xosen

When a post is published or updated, this plugin will send a backup email to the administrator of the WordPress 
blog with an attachment file that contains the post in XML format. The XML follows the format used when WordPress 
exports blog contents so that it can be easily used to restore the post.
The general idea of this plugin is to never loose any of your posts. If you have scheduled a backup of your 
blog once a week, its possible that you will loose the new posts published during that last week. With this 
plugin you will have a backup of all your new published posts in your email account.

New Post Automatic XML Backup by Email

When a post is published, a backup email is send to the admin with the post content in XML format.

Jatinder Pal Singh

This is a simple plugin which is designed to help the posters who some times forget to select the post category and post is published under default category. Once activated, this plugin will force the users to select post category while adding new post to wordpress site. Whenever User tries to publish a post without selecting category, it will give an alert to the user and also highlight the category selection area so that user can see from where to select the post category. 
Moreover, If poster hasn’t selected the category while clicking on publish button, it will save the post as draft under default, so no need to worry about loosing the post content in any case due to this plugin.

Force Post Category Selection

Just found this little gem of a plugin. Its so simple to use, literally just install then forget about it. I have two categories, and needed to make sure at least one of them was selected. This did the job perfectly. Thanks!

Install, then forget. A+

This is simple plugin which forces the users to select atleast one category from the list while publishing a new post.

New Post Automatic XML Backup by Email vs Force Post Category Selection