If the inventions presented at Grand Central Terminal the week of May 21 ever make it into commercial markets, they will surely improve people's lives in various ways both big and small.
Perhaps you're a kidney failure patient who will benefit from Dr. David L. Cull's device to regulate blood flow when connected to a dialysis machine. Or perhaps you are disabled, and need a wheelchair like that of Randall Kwapis, that will carry you easily over rough terrain. From automatic candle extinguishers to a new and better kind of pet nail clipper, the 25 semi-finalist inventions featured at the History Channel's first annual Modern Marvels Invent Now Challenge -- chosen from 4,200 nationwide submissions -- ranged from the clever to the life-supporting.