Vestal Design has come up with a refugee-housing idea, which they call the "SHRIMP"--Sustainable Housing for Refugees via Mass Production. Unlike so many of the schemes that use discarded shipping containers (the reason there're so many containers lying around is that it's cheaper to build new ones than ship them back empty!), they instead designed their house to flat-pack and fit four to a container. Another innovation is to put the houses on pontoons (attached, self-inflating) so they can be deployed on water or land or an unpredictable combination of both. The homes would be built from FSC-certified wood, or Vestal says you could cut up shipping containers to use for material.
The structures look like they would be expensive, but they are meant as permanent housing solutions, not temporary camp shelters--IKEA and Muji have done flat-pack prefab homes before, but aimed at normal home-buyers who have some budget to work with. Architecture for Humanity of course has some great designs online from their Kosovo contest, some of which should be even cheaper and pack smaller than SHRIMP, but it is hard to tell from the information available on both sites. ...However, it may be a moot point. A New York Times article reprinted on AfH pointed out that nations usually don't like foreign refugees to have houses that are too nice, because then the refugees never leave.
Perhaps the best use for nice-but-cheap prefab homes, then, is redevelopment of crisis areas (such as New Orleans now, or war zones after the fighting is over). They could be what enable refugees to move back home. Some of the entries in AfH's Kosovo contest did a good job of designing both for immediate refugee needs and for long-term redevelopment needs.
OB. Hexayurt Plug:
A somewhat lower-tech flat-pack refugee shelter design. Performed very well in the Black Rock desert and is, I believe, going to be in the AFH book next year.