Domain Orders Extended For WHMCS will allow your clients to perform multiple lookup and checkout for domain names in a single request. And all this in the entirely new domain order form in the WHMCS client area that supports gTLDs and ccTLDs! What is more, on the basis of searched domain names, inbuilt domain spinners based on eNom and OpenSRS will display your customers the suggestions that should interest them. This is an amazing functionality that you must have in your WHMCS!
Demo: http://www.modulesgarden.com/products/whmcs/domain_orders_extended/features