Magento module Customer Group Without Tax
Module that allow showing prices without tax for choosen customer group. You can specify which customer groups will see prices without tax on product lists and pages. By default customers will see prices with tax in cart and checkout (if You will set this in standard Magento configuration) but there is also option in this module to overwrite it and show prices without tax also in cart and checkout.
After install You can enable module and choose customer groups that will see prices without tax in System -> Configuration -> JRD Modules -> CustomerGroupWithoutTax