RQ Management 100 Case Studies showing success of a product or service

I have seen success stories described as case studies on the big consultants' sites. Ernst & Young, PriceWaterhouseCoopers, Deloitte, etc.
show how they helped clients save money, etc.

Here's another resource for getting ideas. ABI/Inform database. Type: case studies in SU Subject heading AND information technology in SU Subject heading.
I hope these will find some examples you can apply.