The original Tagg tracker put pet-finder gadgets on the map — literally. The device ($120, plus $10 a month) snaps onto an animal’s collar and uses Global Positioning System satellites to pinpoint lost animals, display locations on a map, and send alerts to your phone. The Tagg Plus measures activity, so you can see if Rover is getting enough exercise and maybe cut back on the Snausages. It also gauges ambient temperature, so you’ll know if he’s cold and needs a cute holiday sweater.