Rumors that Apple is developing a smartwatch have caused a wave of new interest in this relatively small and obscure market. What is a smartwatch? Do they already exist? What can they do?

These are questions that have been asked by others – and answered. A handful of companies (from small start-ups to the biggest electronics companies on the planet) have already crafted these devices and will sell you one right now.

I’m Watch

I’m Watch is the Italian sports car of watches. It’s beautiful, it’s expensive, and it’s designed in Italy. Even the most basic version retails for $449, but if you've got money to burn, you can order the watch in white gold with diamond accents – for just $19,990! Yes, really.

Underneath the shocking price is an impressive piece of hardware. The tiny device boasts a 1.5” LCD display, 400 MHz single-core processor, four gigabytes of flash storage and Bluetooth connectivity. Android 1.6 is the operating system of choice, though it’s been customized for the small, square display. The watch supports Android 4.0/4.1 and iOS  4 or newer.

If you’re not impressed by the specifications, remember – this is a very small device. Compared to the other smartwatches on the market, the I’m Watch is a rocketship.

Pebble

Pebble is the child of one of Kickstarter’s most dramatic success stories. Its creators posted their project hoping a modest response and were promptly overwhelmed by a flood of money that forced them to completely re-think their business. Now, after many delays, the Pebble is available.

Simplicity is Pebble’s main feature. Instead of using a color LCD it relies on a black-and-white eInk display. This keeps the watch affordable (prices start at $150) and ensures it can be used outdoors. Pebble also boasts up to 7 days of battery life. Compatibility spans Android 2.3+ and iOS 5 or newer. Other features include Bluetooth, an accelerometer and a vibrating motor.

Despite its low price, Pebble may be the most practical watch listed here. The low price, long-lasting battery and easy-to-read display make the watch unobtrusive and versatile.

MetaWatch Frame and STRATA

MetaWatch is another start-up that has found traction with Kickstarter. The company currently ships two watches, the Frame and the STRATA.

The difference between the pair is mostly aesthetic. The Frame has a sleeker, more professional look while the STRATA is chunkier and more playful. Inside the hardware is the same with one minor difference – STRATA is rated to resist water better.

Both watches feature a 96x96 black and white LCD display, Bluetooth, vibration for notification and an accelerometer. This puts it roughly on par with Pebble, though that competitor offers a larger display and a higher display resolution. The Frame and STRATA can pair with Android 2.3 or newer, but Apple fans must have iOS 6.

Pricing is a bit higher than Pebble, unfortunately. You’ll have to lay down at least $179.99 for STRATA or $199 for a Frame.

Motorola MotoActv [No Longer Available]

I bet you didn't know Google has already made a smartwatch. Thanks to the wonder of business acquisitions, it’s true. Google owns Motorola, and Motorola makes the MotoActv.

This smartwatch has already been on the market for about two years, and it offers some impressive features. The display is a 176x200 1.6” LCD with automatic super-bright outdoor mode that is protected by Gorilla Glass. Other features include Bluetooth, an FM Radio and GPS.

MotoActv isn’t built for just anyone, however. It’s meant for outdoorsy types who want to access smartphone features while literally on the run. As such, its features are geared towards that purpose. The interface focuses on fitness rather than social networking (though you can use Facebook and Twitter) and the watch is a bit bulky for everyday use. Though originally retailed for over $200, some online stores now sell the entry-level 8GB model for $130.

Oh, and it only supports Android. Athletic Apple owners will have to make do with something else.

Sony SmartWatch

Sony is one of the biggest electronics companies in the world, yet very few people know about the smartwatch it’s had on the market for nearly a year. Even the company’s own website seems uncertain about the details.

Surprisingly, Sony’s option is the least expensive on the market. Amazon currently has it listed for $125. What does it do? Smartwatch stuff. You can receive notifications synced from your smartphone, play music or quickly check your email (good luck, as the display is small) but that’s about it. Like MotoActv, the Smartwatch can only sync with Android phones.

The other options on this list will probably serve you better. But if you want to try out the concept, and you want to spend as little as possible, then Sony’s SmartWatch is the way to go.

Conclusion

The smartwatch remains immature. No one is yet sure what the device is best used for, or how to best build one. Should battery life be a priority? Or is a color screen a requirement? What should battery life be? How big should the screen be? All of these questions are unsettled.

Apple could release a new product that converts the smartwatch from a niche product with uncertain qualities into the next must-have gadget. Or they could never release anything at all. Give one of these alternatives a try while you’re waiting to see what Cupertino’s engineers may or may not be working on.

Would you wear one of these, or the new Apple watch (assuming one ever comes out)?  What priorities do you think a smartwatch should have? Let us know in the comments.