Where are the information sharing stars?

A simple and intriguing performance evaluation approach asks: "Name the top 5 people in your department or across the organization who in your opinion do a great job of sharing information and knowledge for the benefit of others".  For managers, the results are gold: These named colleagues are the go-to people who have built a reputation for always having something to offer to help a project, support a specific task, or teach a technique. 

We information professionals can learn from that phenomenon.  "Who in your department is generally considered to be the go-to, and why?  I'm asking in the context of setting up some new information services."  Naturally, we want to know what the seekers are looking for -- so that we can assess how we might support the go-tos.