The scrolling LED dog tag, available in Japan, lets you communicate everything you want, as long as it can fit onto the little screen. Messages can be up to 118 caharacters in length, and are input using controls at the rear. Scrolling speed and brightness are also adjustable. $40.
Implications - If you can't decide on a simple message to get engraved on a dog tag, this technological alternative gives you a lot more options. Maybe someday these dog tags will hold more than just simple messages and contain all of your personal information; however, until that day comes, you'll have to settle for 118 characters worth of text.