Speaking as an independent IT consultant: Listening and trying to truly understand the problems they have (at least I try to do that as much as possible). Then solving those problems in perhaps unexpected ways. It might sound a bit trite but from my experience business software development often tends to get stuck in a rut and less than optimal or even harmful practices are perpetuated because "it's always been done this way". Cargo cult is an eminent problem in business IT processes that goes unchallenged far too often.

Effective knowledge transfer is another aspect. Not just coding up a solution but teaching others how to solve specific problems by themselves is highly valuable.