This is Cool: Light-up bracelets for the teens
I think what I love about them is that they still involve some of the old school aspects of secret communication: the two bracelet wearers must first sync up their bracelets and then agree on what different vibration patterns and colours mean in their secret communications. It can't really be co-opted for bullying or sexting (I mean, a couple could agree that certain patterns mean dirty things, and the vibration aspect could be -- well you know -- but that's pretty innocuous if you think about it.)
The main downside? These things are expensive which means that the rich kids will have a new toy and it will become even more obvious whose parents don't have $80 to buy them a bracelet (at the pre-order discount!)
If I was a teenager, I would be all over asking for this! In fact, I kind of want one now.
Check them out at Gemio.