Jehovah's Witnesses are known for their missionary activities. Typically, all adult Witnesses are expected to spend a certain amount of time every week "witnessing" to those in their area. Depending on rules in the country, this can take the form of going from door to door talking about their religion or standing in a public place holding up magazines (The Watchtower and Awake!) and responding to questions by passers-by but not soliciting contact themselves.
See also: Organizational structure of Jehovah's Witnesses for more on Jehovah's Witness missionary activities.
The Church of Jesus Christ of Latter-day Saints is one of the most active modern practitioners of missionary work.
Young men between the ages of 19 to 26 who are "worthy," or following church teachings, are strongly encouraged to go on a two-year, full-time proselyting mission. Young women, who must be 21, may also serve 18-month missions. Elderly, retired couples are encouraged to serve missions as well, but their length of service varies from 12 to 24 months. The Church has about 60,000 missionaries worldwide.  (http://www.lds.org/newsroom/page/0,15606,4037-1---6-168,00.html)
Prospective missionaries receive a "call to serve"—an official notification of their location assignment—through the mail and are "set apart" (specially assigned) to preach the gospel. Young men are also ordained Elders. Missionaries generally stay in the same general location for their entire mission. They are, however, relocated within this region every 3 months or so. This area is called a "mission" and is an official geographical area recognized and administered by the Church.
Missionaries pay their own expenses, usually with assistance from family and friends. Missionaries who cannot raise the needed funds may obtain assistance from a fund operated by the church and contributed to by members. In the past, each missionary paid his or her actual living expenses, but this approach created large burdens on missionaries who served in expensive areas of the world, so in 1990 a new program was introduced to equalize the burdens. Now, all young missionaires pay a flat monthly rate which is distributed according to regional costs of living. The current cost of a mission is approximately $400 per month, which covers food, lodging, transportation and personal items. Young people in the church are encouraged to save money throughout their teenage years to pay as much of this as they can, although nearly all receive assistance from family (usually parents) and friends. In some cases, the general missionary fund is used to pay for missionaries' expenses, but the church discourages relying on this fund and prefers missionaries to pay their missions themselves (this particular Church fund is made up of contributions from Church membership and monies are generally not taken from tithing or other Church funds). Elderly couple missionaries pay their own costs.
Newly called missionaries attend a short training period at one of the nearly two dozen Church Missionary Training Centers (MTC). The largest MTC is located in Provo, Utah adjacent to Brigham Young University (BYU) (some housing for the MTC is, in fact, former BYU dorms). Missionaries serving English-speaking missions spend three weeks at the MTC and are trained in the use of proseletizing materials and taught expected conduct. Missionaries bound for foreign-language missions spend longer periods at the MTC—eight to ten weeks—in order to learn the language. During this period, they are encouraged not to speak in their native tongue, but rather immerse themselves in the new language. Other MTC campuses exist in other parts of the world for missionaries serving in their native countries outside the US.
MTCs and their teaching methods have reportedly been studied by various organizations because of the rapid ability of the missionaries to learn a foreign language in the setting. Occasionally, missionaries are said to be fluent in the language they study at the end of the eight- to ten-week period.
Full-time proselyting missionaries are required to adhere to a dress code: for men, dark trousers and suit coats (which are optional in hot climates), white dress shirts, and ties are required; for women, modest and professional dresses or blouses and skirts must be worn. Casual clothes may be worn when providing manual labor or during "preparation day" (called "P-day" by missionaries) when the missionaries recreate and do their cleaning, shopping, and laundry. All full-time missionaries wear a name tag that gives their surname with the appropriate title ("Elder" or "Sister" in English-speaking areas) and bears the church's logo.
In the past, church officials expected young men to serve missions regardless of marital status. Today, however, young married men are not expected to serve missions, unless specifically invited by leadership to oversee a mission. This call is typically extended to the couple, and in turn the entire family.
Older, retired couples are also encouraged to serve missions and may serve as long as they desire (typically from one to two years). Many older couples have been known to serve several consecutive missions, which may include proselytizing, service, historical/historical re-enactment, temple work or to fulfil various other needs of the Church.
Besides the above-categorized missionaries, the LDS church also has a strong welfare missionary program. The missionaries who serve these types of missions typically serve in poor and third world countries and do not actively proselytize. Regular proselytizing missionaries typically engage in welfare activities and community service for a few hours a week.
Completing a mission is often seen as a rite of passage or crucible for young LDS men, and most tend to regard it as a positive event: The phrase "the best two years of my life" is nearly a cliche among returned missionaries when describing their experience.
It is perhaps unsurprising, however, that with many thousands of young men acting as missionaries, that some have negative expirences, or regard their missionary tenure poorly. Some report that they serve missions not out of genuine desire to do so, but due to peer pressure, or due to cultural and familial expectations.
The most visible missionaries are typically those who proselyte door-to-door and ride bicycles for transportation, but not all missionaries engage in these activities. There are "service missionaries" who solely volunteer in impoverished areas, do genealogical research, and are tour guides. In many areas, even proselytizing missionaries spend most of their day responding to incoming phone calls, queries, etc., and use public transit or drive automobiles owned by the church.
- Baptist International Missions, Inc. (http://www.bimi.org)
- Baptist World Missions (http://www.baptistworldmission.org/)
- The Official LDS MTC website (http://www.mtc.byu.edu/)
- LDS Missionary Training Centers article (http://www.lightplanet.com/mormons/daily/missionary/MTC_EOM.htm)
- Christian Missionaries in South Africa (http://home.telkomsa.net/south_africa)