Meet DoubleFlex: a portable home gym that uses SpiraFlex resistance technology to give you a total body workout. Just use 5 lb. rated FlexPacks to adjust the resistance level. The whole package weighs less than 2 lbs but lets you add up to 15 lbs. of resistance. You can use it to work on your abs, thighs, back, and other parts.
The kit comes with 9 workouts and a 50-page guide to get you started. More information is available here.