Papers on IT Business Models

I take care of IT for a rapidly growing ISV. We are reaching the stage where IT management is getting more complex. I want to find documents relating to the methods that are commonly used for managing IT costs and billing. How are companies definingtheir technology budgets ? are departments billed ? how much ? what is a cost that can be considered corporate ? gartner et al state that desktop support costs can equal ABC dollars per user, but what about server costs ?
thanks