It was the promise of the Jetsons: Get a robot to do all your cleaning for you and never have to pick up a dust rag again. Reality has been disappointing, but there's one little gadget that promises to keep your floor clean without (much) thought from you. Have you ever tried the automatic vacuum, the Roomba, in the kitchen? Or its sister Bravaa, the one that mops? I'm just really curious — do these things actually work?