Business::onlinepayment::tclink is a business::onlinepayment backend module for the trustcommerce payment gateway. it is only useful if you have an account with trustcommerce: http://www.trustcommerce.com/

business::onlinepayment is a generic interface for processing payments through online credit card processors, online check acceptance houses, etc. (if you like buzzwords, call it an "multiplatform ecommerce-enabling middleware solution").