Chipolo ($19) is a virtual leash connected to your smartphone via Bluetooth. So you can attach it to your dog’s collar, let him run wild on the beach, and then find out exactly which immaculately built sand castle he’s delicately hiding in when it’s time to go home. You can also use it to find your phone by giving it a quick shake. It finds anything within 60 meters (about 197 feet), and sends you a notification when it’s in and out of range. Works with both Android and iOS devices too.