Maestrina, by Leo Nabuco @ Flickr, Some Rights Reserved
This paper shared by Jan is good read on service catalog and how one should look at it. For starters we should look from the point of view of the ones using it.
End users and business managers (customers) see and expect different – even if related – outcomes from IT services. As referenced in the paper, Joe Peppard distinguishes two types of value of IT services:
User utility – Which is defined as the benefit a user or community of users attaches to a particular service, based on the usefulness of the service to them in the performance of their jobs.
Organizational benefit – Which is based on the extent to which the service supports the organization in achieving its business objectives.
ITIL Blues 