Another alternative way to travel lightly, while making a difference to the world:

WWOOF - World Wide Opportunities on Organic Farms, or Willing Workers on Organic Farms. Est 1973 in the UK.

Learn about organic farming, and about sustainable lifestyles while helping others.

Voluntary work in exchange for meals, a bed & education.

A great way to know an area, experience new cultures, and spend time in nature.