This has to be one of the laziest questions posted on here for some time.
The short answer is that, other than lose sensitive data, MCs work at all levels of government and provide the full range of services.
This includes: setting policy, designing the correct portfolio to deliver the polocy, manage implementation, business analysis, system development, process re-engineering, right down to noddy project support.
You should think about which companies you are interested in and do some research. This information is not a secret and can be found on all good company websites.
Hope that helps