Encouraging companies to finally put effort into understanding their most important asset, their people, is often harder than it should be, so congrats! First, some full disclosure, I'm the CEO of WhoKnows, and we have a platform that addresses exactly the problem you're facing, so I apologize if this comes across as a sales pitch. However, I honestly believe this could be a case where the product is the best answer to a question.
Basically, we have built a machine learning platform to automatically consolidate existing profiles and then analyze online content and work activity to automatically build a private network of expertise and relationships. All of this is done with a focus on the employee's privacy, and over 90% of our users now have up-to-date comprehensive profiles about what they know. We're already deployed at multiple F500 and mid-market companies and have passed numerous privacy and security audits across the world.
Rather than continue pitching on the forum, feel free to reach out to me at chris@... if you'd like to hear more!