I would suggest that one of the most striking examples of a group that is innovative in the field of Catholic Social Thought would be the Missionaries of Charity.  Founded by Mother Teresa, this group advocates that a pure outreach between the work of social work towards the "poorest of the poor" needs to be linked to spiritual doctrine.  Founded by Mother Teresa, the group advocates that spiritual worship must be supplemented with real time service.  Mother Teresa embodies this in her own life.  She left her order and began work as a free nun.  In doing so, she embodied how Catholic Social Thought must be linked to service of others. Members o the Missionaries of Charity "took vows of poverty, chastity, obedience, charity, and an additional, special vow to serve the truly destitute."  Her group demonstrated that spiritual fervor is only matched with deeds and service, suggesting very clearly that Jesus' work does not remain in the halls of worship as much as it does in helping others as the human representation of "doing God's work."  

The Missionaries of Charity is a group that not only influenced teachings in Catholic Social Thought with its ideas.  It is a group that would meet Pope Francis's call to reinvision the church in a light that speaks more to service:  "I prefer a church which is bruised, hurting and dirty because it has been out on the streets, rather than a church which is unhealthy from being confined and from clinging to its own security."  Certainly, this standard is met with the Missionaries of Charity, a group that combines their erudition in Catholicism with the reality of social service to those who need the most of help.