I am in need of a module, gadgets, whatever that will log each document access, recording the user id and document accessed. We have thousands of documents that users will be accessing on a subscription basis and each document costs them a set access fee. I have an idea how I can code this, but if there is a module all ready out there I would rather go that way.

Edit: I guess I should add that this is not a typical Shopping cart type of thing where they pay at time of access. They have an account setup with us and are billed at the end of each month for their total fees, including fees for other services. So I need a way to pull reports for each user for audit purposes and billing.

TIA