There were a lot of robotic vacuums at CES this year, but Monueal's latest flagship really impresses. It can mop as well as vacuum, and a small wall-mounted sensor can detect when enough dust has settled for vacuuming to be necessary.
You can customize this robot's schedule using a smartphone app, or, if you're less into micromanagement, you can just leave it plugged in and let it decide when to clean. It's a perpetual motion vacuuming machine. And best of all, it's $100 less expensive than the comparable iRobot vacuum.