Would have the basic usage of "experts exchange" or "stackoverflow", site, but for internal users, both on the portal and could be used internally.  It would also be great to incorporate a badge/point system to use a little gamification to invoke more use.  These forums could also be used to create new issues if it couldn't be solved, add to a knowledge bank, and or a known error database.  Take it a next step and build it so that you could attache these as suggested hints when submitting calls, or based on text entered into a call these articles are "Suggested" to promote self help.