Does anyone know if it's possible to create one of the stores with magento where visitors have to log in first before being able to browse through categories and products?
I need it for one client who wants to have a section for retail and separate for wholesale customers.
The best solution would is use Magento Enterprise, which offers this feature (called Private (Club) Sales including Events, Invitations and Site access permissions in the comparison chart) out of the box.
http://www.magentocommerce.com/magento-connect/MagentoPycho/extension/3954/store_restriction might work.