Product owner
Think of the product owner as the glue that binds everything together. He promotes the interests of clients and team members alike, focusing on the added value of the product to be delivered.
Implementation manager
Don't just build a system, get it implemented. IT projects are notorious for their failure rate. In part, that's due to poor implementation of the system.
Business Analyst
Business analysis is the set of tasks and techniques used to work as a liaison among stakeholders in order to understand the organization.