The NYMI wristband is a biometric device that uses the unique cardiac rhythm of your heart to identify you. It then transmits over low Power Bluetooth to an Authorized Authentication Device (AAD) (a smartphone, tablet or computer).
This can then authenticate you for websites or any other connectable device that uses bluetooth. News is out that the NYMI will have a built in bitcoin wallet, though I don’t see that posted anywhere on the NYMI website news about the bitcoin wallet has been posted on twitter.
Take a look at the site here. Don’t forget this will also be useable as a password authentication device in it’s own right. At the moment you can pre order the device for $79 though shipping is stated as mid 2014.