Few product categories get a second chance to make it big. Wristwatch calculators, 8-track tapes, mopeds, unicycles and Polaroid film are never going to be wildly popular again. But tablets are poised to make the kind of comeback that would make Robert Downey Jr. proud.

PC makers have offered slates and convertible notebooks for nearly a decade, and they've never caught on. But now, a new generation of attractively designed and low-priced screens are looking to lure in consumers. Most of these sleek slabs of glass rely on simplified touch interfaces and will probably work best as content consumption devices: Something you'd use for reading, web browsing and watching movies.

The new generation of tablets might just pull it off. So far, Apple has sold more than 500,000 iPads and it says it can’t keep up with the demand, suggesting that computer makers are right to jump on this trend now.

As they do, they're exploiting the iPad's weaknesses. Typing on the iPad isn’t easy and it is an underpowered device for its price tag – the same money could buy you a nice laptop. Its browser doesn't support Adobe Flash, and you can't run software on it unless that software comes from Apple's App Store.

So if you don’t want to buy into the Apple hype machine, there are plenty of alternatives. From Dell to HP, almost every major PC manufacturer is working on a tablet. And there’s no dearth of upstarts. Asian brands and European startups are vying to get their tablets out, too.

Wired looks at some of the most interesting screens that will get into consumers’ hands this year.

Above:

JooJoo ——

JooJoo (nee CrunchPad), the tablet from the Singapore company Fusion Garage, is an ostensible competitor to the iPad. It launched on the same weekend as the iPad and is very Apple-esque in its hardware design. But the JooJoo is far from being a device that could change the future of computing.

With its 12.1-inch display, JooJoo is a plus-sized monster that is almost a pound heavier than the iPad and offers half the battery life. It runs a custom operating system based on Linux and supports HD videos and Flash.

But in the days after its release, JooJoo has been buggy with surprising user interface glitches and at times difficult-to-navigate screen. And without access to apps or the ability to install your own software, JooJoo is a dumb terminal. It's good enough to check Facebook, Twitter and read websites, but not much more.

A few hours with the JooJoo and it raises the question: Do you really need a tablet? That's not the kind of question a tablet maker wants to raise.

Price: $500

Availability: Online order through JooJoo’s website

HP Slate ——–

In the last few weeks, the HP Slate has caught the attention of gadget heads, thanks to teaser videos that have been trickling out about the product.

In terms of looks, the Slate looks like the iPad’s twin. It shares the Apple tablet's sleek profile and large capacitive touchscreen. Leaked product specs suggest the Slate will have an 8.9-inch display, 1.6-GHz Atom processor, Wi-Fi capability, optional 3G access and a pen/digitizer support.

It will run Windows 7 and support Adobe’s Flash technology. It is also likely to have a built-in camera, video-recording capability, a USB port and SD card reader – all features pointedly aimed at the iPad, which lacks these features.

A big drawback is likely to be the five hours of battery life that the device promises. After all, do you really want to worry about keeping yet another gadget charged all the time?

Price: Rumored pricing of $550 or $600 depending on 32 GB or 64 GB of storage

Availability: Expected to launch later this year

Dell Tablet ———–

Unlike its rival HP, Dell has been bold enough into dip its toes in the mobile phone market and create its own handset. But can it pull off a tablet too? This year, Dell hopes to make a splash with the Mini 5, a Sony PSP-sized tablet that will have a surprisingly small 5-inch screen.

That display is only a little bigger than that of an iPhone or a Motorola Droid, but Dell is counting on the fact that people want a compact computing device. After all, not everyone wants to rush out and buy a new bag just to carry around their tablet.

The Dell Mini 5, which will be the first tablet from the company, will sport a 5-megapixel camera on the back, a separate front-facing camera that can be used for video conferencing, a standard 3.5mm headphone jack, Wi-Fi, 3G connectivity and a Qualcomm Snapdragon 1-GHz processor.

The Mini 5 will run the latest version of Google’s Android operating system, version 2.0 or higher. And instead of the 4:3 aspect ratio of the iPad, Dell’s tablets will support the 16:9 widescreen ratio, so movie watching should be a better experience.

If you think the 5-inch is not for you, Dell says it has more. Dell also has a 7-inch screen and a 10-inch screen tablet codenamed 'Streak' in the works. The 7-inch tablet could be available this year, while the iPad-sized 10-inch device might hit the market next year, says Engadget.

Price: Not known

Availability: Expected this year

WePad —–

Closer to the JooJoo in size than the iPad, the German-designed WePad is a tablet built on Android. The WePad will have a 11.6-inch touchscreen, two USB ports, a 1.3-megapixel camera, Flash support, six-hour battery life and a 1.6-GHz Atom processor. (See more specs (.pdf) for the device.)

The WePad will support most popular e-book formats, including EPUB, and will even have a magazine reader app.

Neofonie, the company behind the WePad, plans to offer a 3G and a Wi-Fi model.

But American consumers can only lust. The WePad will be available in Germany and, later, Europe, but not in the United States.

Price: 16-GB Wi-Fi model to cost around $600; a 32-GB 3G version to be around $775

Availability: Pre-orders start in Germany April 27; shipping expected in July

Google Chromium Tablet ———————-

“An e-reader that would function like a computer” – that’s Google vision of a tablet. The search giant is not afraid to get into any new business and the flavor of the season, tablets, seem to have caught Google’s attention.

According to a report in The New York Times, Google is working on a tablet that would run the Android operating system. Earlier this year, a Google interface designer created mock-ups that showed a Android tablet at work.

Google's tablet mock-ups indicate a device that would have icons providing quick access to Facebook, as well as Pandora, Gmail, Google Calendar and other Google apps. It would support multitouch and the familiar pinch-to-zoom and scrolling gestures.

Google has already launched its own smartphone, the HTC-designed Nexus One. It’s not much of a stretch for the company to get into the tablet business next.

Price Unknown

Availability: Unknown

Notion Ink Adam —————

Tablets are not just for big companies with outsize marketing machines. Or so believes Notion Ink, an Indian startup that’s never made a hardware product before. The company is hoping to take on the big guns with its home-brewed design.

Notion Ink has some ambitious plans for the Adam. If it can pull it off, Adam will be among the first devices to use Pixel Qi’s displays, which would allow it to switch between a low-power, black-and-white display and a full-color LCD mode with the flick of a button.

The makers also promise a 10-inch display, a 3-megapixel camera, an Nvidia Tegra CPU, and a whopping 16 hours of battery life.

It will be just a tad heavier than the iPad, say the creators, and will come with Wi-Fi and 3G access.

Whether Notion Ink can actually pull it off remains to be seen. After all, making a tablet isn’t easy for a startup. Just ask JooJoo.

Price: $350 to $800

Availability: July

Archos 7 Home tablet ——————–

Archos has been cranking out tablet-style devices for a long time now. But their tricky interfaces and bulky hardware have never become popular with consumers.

Yet Archos isn’t one to give up. The company’s latest tablet, the Archos 7 Home, hopes to ride the Android buzz with a 7-inch touchscreen. The tablet will be powered by a 600-MHz ARM 9 processor, include Wi-Fi capability and have about seven hours of battery life, the company promises.

Archos is also working on another Android tablet with an 8-inch screen. But considering its past products, it’s difficult to get very excited about these devices.

Price: 150 euro, or about $200

Availability: Europe in April, North America later this year

ICD 'Gemini' Tablet ——————-

Ever heard of Innovative Converged Devices, or ICD? Neither had we. But there’s something about the tablet business that seems to draw in intrepid entrepreneurs.

The Seattle company is creating a line of Android tablets with displays ranging in size from 7 inches to 15 inches that will be distributed through wireless carriers.

ICD’s Vega tablet, a 15-inch “home hub,” has already found a taker in T-Mobile UK, though the two companies have yet to disclose pricing or launch date.

Now ICD is working on a tablet called Gemini that will have a 11.2-inch multitouch display. The Gemini’s specs could certainly give the iPad a run for its money: It will have a 1-GHz Tegra Nvidia chip, a SD card reader, an FM radio, GPS, Wi-Fi, 3G and a 2-megapixel camera in the front and a 5-megapixel camera at the back.

Impressive as the specs may be, there’s more to a tablet than hardware. There’s no word on software and user interface for the ICD devices, and few humans have ever set their eyes on this beast.

Price: Unknown

Availability: Unknown