Extension pour créer un nouveau champ dans le formulaire d’inscription de Magento

Customer Attributes (payant)
Add new fields to registration form – e.g. ‘how did you find us’, gender, VAT number, etc. The fields can also be displayed at the billing information page of checkout.

http://www.magentocommerce.com/magento-connect/Amasty/extension/3024/customer-attributes