In a new article on phpnuke moajosh announced the Accounting-module, running PHPNuke, NukeCommerce and osc2nuke.

moajosh "This module was written for customers to use to view their account status. Admins can manage invoices, services attached to each invoice, view paid/unpaid invoices, manage users, and much more! Get this module here See a demo here: username: user password: user"

see Accounting-module (demo) :: download right here :: feedback via mailer