OpenTools_Ordernumber
This is a module to modify the order, invoice, shipment and credit memo numbers in Magento. Many variables and counter options are available in the format string.
Installation
Install via modman:
$ cd <magento root>
$ modman init # if you've never used modman before
$ modman clone ssh://open-tools.net@open-tools.net/var/www/open-tools.net/private/git/Magento_Ordernumber/
Configuration
Visit System -> Configuration -> Sales -> Customize Order Numbers and set it to Yes to enable custom numbers for certain number types. All configuration is done there, there is no separate component or view available.
Usage
Note that it's disabled by default.