Employee Evangelism will increase sales, increase relationships, increase brand visibility and result in people caring more about the organization, because they start to care more about the people in the organization.
Starting an Employee Evangelism program is not that hard. Take a small group of people that are already doing it, probably in a less organized and intentional way, and train them in the tools and messages that make it easier and more effective. Once that team is doing employee evangelism well, have them mentor others in the organization and grow your buzz with each person.