Everything is a cost center even sales until you start looking at larger chunks of an organization. As long as you can demonstrate an increase in profit you can easily justify a huge salary regardless of what part of an organisation you work for. 'I did X which generated Y cost savings' works just as well as 'I brought in X business at Y profit margin generating Z profit.'

edit: Typical examples include research and development, marketing and customer service.[1] http://en.wikipedia.org/wiki/Cost_centre_(business)

PS: I updated the data entry screen, increasing our call center's throughput by 3% creating 5 million in savings over the next 3 years.