"Part of our investment in short-term missions is the completion of our new Volunteer Mobilization Center, a 16,000-square-foot facility in Orlando that will be used to mobilize thousands of volunteers heading out on short-term missions," said Bruce Smith, president and chief executive officer of Wycliffe Associates. "Designed and built primarily by volunteers, the center will service a growing tide of American's seeking to use their free time more productively."

Roger Peterson, president of STEM International -- Short Term Evangelical Missions -- (www.stemintl.org), estimates that 50,000 churches in the United States are sending members out on mission trips each year.

As one example, White Memorial Presbyterian Church in Raleigh, North Carolina, had almost 200 members go on 15 foreign and domestic mission trips in 2007, according to Danita Morgan, director of missions. The foreign nations were Haiti, Northern Ireland, Poland, Russia and Mexico. Several White Memorial members took the mission trip to Mexico with their teenagers in lieu of the time-honored spring break trip.

Global Crossroad (www.globalcrossroad.com), a for-profit firm based in Baton Rouge, Louisiana, arranges volunteer vacations in 34 countries. It is one of more than 3,000 nonprofit and commercial enterprises catering to travelers who are more interested in serving than being served.

Mission Maker Magazine (www.missionmakermagazine.org) with a circulation of 150,000, is another example of just how large this phenomenon is. It is a full-sized, full-color, multi-page magazine whose editorial and advertising serve North Americans interested in Christian missions throughout the world.

Back in 2005, David Bernstein of Satisfaction Magazine quoted Doug Cutchins, co-author of the book "Volunteer Vacations: Short-term Adventures That Will Benefit You and Others," as saying "this phenomenon continues to grow."

"It's gone on in small ways for a very long time," Cutchins said. But the September 11, 2001, terrorist attacks brought on a surge of interest in this small, but growing segment of the travel industry, according to Cutchins.

The 2004 tsunami disaster that wrecked havoc on Thailand and Indonesia sparked even more attention to service-oriented tourism.