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