107 Lena Ann Drive
St. Cloud, FL 34771
This Christian group has a wealth of information on short-term mission trips. They provide conference information and other resources on short-term missions, along with an online bookstore.
Although they no longer directly organize short-term mission trips, they refer people to Orpanos (near Memphis, TN) for that purpose (see the STEM website).
In 2013, moved their headquarters from Minnesota to the Orlando, Florida area.