Modernizing the measuring cup seems like a silly idea at first. The glass Pyrex 2-cup measure has worked well in kitchens for generations.
When measuring sticky ingredients, like peanut butter, some is always left sticking to the sides of the traditional measuring cup. With this gadget, as the bottom of the adjustable cup is pushed up, the sides of the tube are scraped into the mixing bowl -- no spatula scraping required. As Alton Brown ($13.99 for a 1 cup and 2 cup plunger) says, "squoosh out every last particle . . . no waste."
Even the gadget-phobes at Cook's Ilustrated like the Adjust-A-Cup calling it "ruggedly constructed with a very tight seal between plunger and tube." Unlike some similar products, the Adjust-A-Cup is diswasher safe.
Attention BBC Food fans: the Adjust-A-Cup is useful for "translating" recipes since it measures in cups, pints, mililiters, and ounces -- with seperate measures for wet and dry ingredients. Be sure to follow instructions about using a bit of oil to grease the seal in the Adjust-A-Cup or the tool can get stuck together.