I have mentioned this Sony Ericsson MBW-100 Bluetooth Watch quite a long time ago. Here is a short video preview.
The Sony Ericsson MBW-100 has an OLED screen and interact with your phone via Bluetooth, when there is a call, it will show you the caller ID and it will notify you if there is a SMS. It will also alert you if the watch goes out of the Bluetooth range. It can also control the music player of your mobile phone.
Watch the video after the break.