I spent some time this morning poking around on the U.S. Center for World Missions website. If you haven't checked it out before, please do (www.uscwm.org). It will be worth your time. Here's an excerpt from their front page:
God deserves praise, glory and obedience from all peoples.
But 10,000 people groups do not yet have a community of disciples among them who can witness to His true nature.
The U.S. Center for World Mission (USCWM) is a community dedicated to making the glory of God fully known, and to bringing all the people groups on the earth to worship and obey God (as revealed in the Lord Jesus Christ). The USCWM produces and publishes resources to motivate and equip Christ's body to join Him in His Biblical purpose to "bless all the families of the earth" (Genesis 12:1-3). The USCWM also engages in a variety of activities toward ensuring, as soon as possible, that each distinct people group is "reached"—that a viable movement is established to evangelize and disciple each people group.
Churches and prospective missionaries face many obstacles to effective involvement in reaching unreached peoples. Mission agencies and field missionaries face another set of obstacles. By gathering, applying and publishing insights in each of these realms, the U.S. Center for World Mission advances shared solutions to common hindrances in the mission effort.
"You are worthy to take the scroll and to open its seals,
because you were slain,
and with your blood you purchased men for God
from every tribe and language and people and nation."