This extension adds a column "order count" to your Magento customer grid.

There are two versions of this extension:

Branch "master"

• add column using event/observer pattern, see http://www.webguys.de/magento/turchen-23-pimp-my-produktgrid/
• highly compatible solution
• no csv export for this column

Branch "csv"

• add column using plain old rewrite
• less compatible version, you could have some conflicts with other extensions
• supports csv export for this column