One Japanese company is developing a device to help with those moments (because you were drunk) that you might not remember (due to drunkeness) that you set down your phone (to hold another drink) and forgot to pick it up (surprisingly, just due to a general poor memory). The device fits in your pocket and communicates at all times with your phone. When you move outside of 5 meters, it beeps, shakes, and generally annoys you so you don't leave the phone behind.
It sounds like a drain on the battery, and were not certain exactly what technology is being used, but it might be better than having no phone at all. Of course, I usually remember my phone when I find myself unable to drunk-dial an address book of hot female "just friends." It's nature's way of keeping me with my phone. As for commercial device, we have no word on absolutely any production specifics yet, but we'll keep an eye out for more. [theinquirer]