Sony is showing a splash-proof SmartWatch that is 0.3 inches thick, with a 1.3-inch color OLED 128x128 touchscreen . It uses Android 2.1, and can be attached to a wristband or to your clothes. Bluetooth connects it to your Android smartphone, and it is optimized for Sony's Xperia line of phones.

The device can be used to answer (or not) incoming phone calls, read text messages or e-mails, or control music on your smartphone. You can also use it to remotely snap a photo using your smartphone for those group pics, and photos can be deleted or shared from the watch. Already, about 200 apps are available for the watch on the Google Play Android marketplace.

Cookoo, I'm Watch

A company called Hama is showing the Cookoo, 0.6 inches thick with an analog clock as well as a digital display. As with Sony's SmartWatch, the Cookoo connects to a smartphone through Bluetooth, and shows missed/incoming calls or calendar reminders, has a location finder that causes your misplaced phone to emit a sound, and plays music on your smartphone, among other functions.

Another device, called I'm Watch, runs a custom version of Android, is 0.4 inches thick, and has a 1.5 inch TFT display. It also connects via Bluetooth to a smartphone -- obviously a central function for these devices -- and works with either Android or Apple iOS devices. It has a feature that tells you if your smartphone is out of range, and also offers a variety of smartphone-related functions, including a display of e-mails, social media notifications, news, weather and so on. I'm Watch also has a connection to cloud storage called, appropriately enough, I'm Cloud, for storing apps and data .

Worth the Time?

Other models have the same basic pattern of functions and support for an accompanying smartphone -- the Meta Watch, Casio G-Shock GB-6900, and the Martian among them. The Casio model has a function that beeps or vibrates to indicate e-mails or calls have arrived on your paired smartphone, and it has the ability to reset itself if you travel between time zones, by syncing with your phone.

The Pebble Watch, which raised a large amount of funding on the crowdsourced Kickstarter Web site and initially raised the visibility of smart watches, is expected to be released soon. Smart watches as a genre have been nurtured by Kickstarter, with Cookoo and the Meta Watch also having received funding from interested supporters on that site.

Prices for the smart watches range from about $180 to about $400. Although the Pebble Watch received a lot of attention because of its fund-raising success on Kickstarter, none of the smart watches have so far been proclaimed a home run.

They largely appear to be serving as remotes or extensions of a smartphone. Since your smartphone is sitting in your pocket or on your desk, a key question is whether these devices add much value in exchange for the time it takes to set them up, learn and manage them, not to mention the price.