One idea that has been gaining popularity the last few years is volunteer vacations, which allow you to use your skills -- teaching, construction, or health care, for example -- to help communities in need around the world. At the same time, they offer an opportunity to explore an area and culture typically off the tourist path.
Global Volunteers (800-398-8787, globalvolunteers.org) and Cross-Cultural Solutions (800-380-4777, crossculturalsolutions.org) host programs running anywhere from one to 12 weeks in locations such as the Lakota Reservation in South Dakota, Ghana, and the ancient Golden Ring towns of Russia.
Earthwatch Institute (800-776-0188, www.earthwatch.org), a pioneer in the work-for-fun travel genre, also sends willing adventurers to all corners of the globe on science- and environment-based excursions.
Depending on length and location, these types of trips run anywhere from $700 to $5,000 per person, including meals and lodging, but not airfare -- a small price to pay for a truly unique (and altruistic) experience.