This plugin allows you have custom order statuses in WooCommerce.
I needed the custom status' to tell customers when I had
- recieved money (if a BACS order)
- delivered to the postal service
and many more. That way I could automatically send an email to the customer updating the status in their end as well.
Read more about how I use it here: http://www.woothemes.com/2013/01/case-study-designgrotten