Paul Elkins tours the country in his "stealth" camper. The tiny domicile took him just $150 to construct, weighs only 60 pounds, and can be pulled by a bicycle. Inside, he's got a stove, a sink, a little bit of counter space, some storage, and a bed. It's even insulated and has a skylight!
Downloadable plans: http://www.elkinsdiy.com/plans/