I would like a quadcopter that takes and incorporates a smartphone into its build. Smartphones have GPS, tilt sensor, accelerometer, electronic compass, decent quality cameras (on both ends, with image stabilization and a bunch of other neat features), they have Google Maps for crying out loud, you could just draw the flight plan on the screen and it would do the rest. Phones have multiple connectivity options for redundancy, downloadable software, processing power out the wazoo, a smartphone would be the perfect on-board controller for such a device. The quad would be a glorified phone casing with a battery, motors and ESCs. Maybe a mirror to point the camera into the desired direction. Why not? Sure, a phone weighs (much) more than the average controller system-on-a-chip, but the benefits outweigh (hah) the weight issue.
Granted, the added weight of the phone, and the larger motors to compensate for the extra weight, and the larger battery to compensate for the extra power drain to lift the extra weight, and so on, would probably take the whole thing above 250 grams and it would require license and registration to operate within the United States BUT HEY, details details.