Potential
These rings add a gripping new meaning to “shake on it”.

Each “smart” ring stores your details, transferred there via a digital business card the size of a credit card. To pass along your details to a new business associate, simply shake hands, instead of handing over a traditional business card. It also displays a contact list of all the people you've exchanged information with – personal info, contact numbers, and for those with short memories, the date you met. All information is customizable, and transferable to anyone wearing another “smart” ring.

To view the information, sync the ring back to the digital business card. No batteries required either; the rings are juiced up by body heat. The entire business world will have to get one of these for the trend to take off in a big way, but even from where I'm sitting, the possibilities are mind-blowing.