Laptop design used to be about combining portability and power to allow business users to perform essential tasks on a machine small enough to fit in a shoulder bag.
But over the past ten years, manufacturers have pushed the boundaries of design and now if you go into PC World, you'll see as many ultrasmall netbooks with sub-10in screens as desktop-replacement machines capable of outperforming many desktop PCs.
Increasingly, laptops need to include something different to stand out from the crowd, and trade shows such as this week's CeBIT are brimming with novel designs that capture the attention of techies, even if they don't encourage the masses to get out the credit card.
So here's PC Advisor's selection of the 10 weirdest and most innovative laptops of all time.
Asus Dual-Screen Laptop
Asus demonstrated at CeBIT this week a dual-screen laptop which replaces the keyboard with an additional touchscreen display.
The Taiwanese manufacturer said the prototype could be used as a conventional laptop, a multimedia hub or an e-book reader. The use of the touchcreen provides an input mechanism that's both flexible and intuitive, according to Asus. The company said the system could be controlled using hand gestures, handwriting recognition and multi-touch.
However, by disabling the software-based keyboard, the laptop can also be turned into an e-book, which can be held like a conventional book in which pages can be moved through touch or gestures.
Next page: More dual-screen laptops
Lenovo ThinkPad W700ds
The ThinkPad W700ds has a 17in primary display and a 10.6in secondary screen which extends from the lid to give mobile users a multi-monitor experience. The "mobile workstation", as Lenovo calls it, also comes with customers' choice of quad-core Intel Core 2 processors and Nvidia Quadro mobile graphics CPU with as many as 128 cores. It's available with as much as 8GB of DDR3 memory and a pair of hard drive/solid-state drive bays for up to 960GB of storage.
"This is the nitro-burning drag racer of ThinkPads," said Craig Merrigan, vice president of global consumer marketing for Lenovo, at the ThinkPad W700ds's launch. It doesn't come cheap, however. Various UK stores are selling the laptop from upwards of £3,500.
Neither can Asus lay claim to building the first laptop with a touchscreen keyboard. The One Laptop Per Child (OLPC) project has been working on a second generation of its so-called "$100 laptop" which is nearly half the size of current XO laptop and consists of two touchscreen displays.
The XO-2 doesn't include a keyboard, but instead will feature a software-based touch-sensitive keyboard. Nicholas Negroponte, chairman of OLPC, said last May that the XO-2 would launch in 2010. "The XO-2 will be a bit of a Trojan horse," he explained. He said the XO-2 will be pushed first as an e-book reader with the capacity of holding over 500 e-books.
Next page: The netbook keyboard
Asus Eee Keyboard
One thing Asus was first with, however, is the netbook keyboard. The Eee Keyboard includes a built-in 5in touchscreen, while a fully functioning netbook is located under its keys.
Like many netbook PCs it has an Intel Atom processor, runs Windows XP Home and has an onboard 16 or 32GB solid state disk (SSD) drive.
It will hook up to larger displays via wireless Ultrawideband HDMI and also boasts Wi-Fi and Bluetooth 2.0. There are also USB 2.0, VGA and HDMI ports and connections for headphones and microphones.
Asus demonstrated the Eee Keyboard at the Consumer Electronics Show in January, saying it would allow users to connect to the internet wherever they are, with no need to carry around an extra computer.
Watch the video below to see Asus' Eee Keyboard in action.
Asus Eee PC 701
Of course, it was the original Eee PC that kickstarted the netbook revolution, with Asus credited with inspiring me-too products from the likes of Dell, HP and Acer when it showed off the Eee PC 701 at Computex in 2007.
For a fraction of the cost of competing ultramobile computing devices, the Asus Eee PC 701 delivered a highly functional portable that appealed to road warriors and students who wanted an unobtrusive and inexpensive computer for basic web surfing, word processing and email.
The Linux-based Eee PC 701, with its 7in screen, was released at the end of 2007, and within a year there were countless competitors, including a dozen different Eee PCs. Asus announced this week that it will discontinuing the original 7in model, focusing instead on larger versions of the product.
Next page: The smartphone laptop
Sometimes, even a netbook is overkill for connecting to the web and performing run-of-the-mill tasks, according to Celio Technology. The company describes its RedFly as "the world's first and only smartphone terminal", and says it provides "a big screen for all the great things your smartphone can do". (See our Celio RedFly review.)
The Celio RedFly connects to Windows Mobile smartphones, giving them a readable 800x480-pixel screen and a cramped but usable qwerty keyboard. In theory, it's possible to do real work such as composing emails and editing Microsoft Office documents on a smartphone.
The Redfly is small (25x152x228mm), light (0.9kg) and inexpensive (compared with a laptop) and has great potential for road warriors.
HP Pavilion HDX
At the other end of the scale is the HP Pavilion HDX. Superfast, with great sound and a huge 20.1in screen, the HP Pavilion HDX is a 'portable' entertainment system aimed at digital editors, artists, multimedia enthusiasts and gamers. (See our HP Pavilion HDX review.)
The HP Pavilion HDX we looked at two years ago came maxed out with the 64bit version of Windows Vista Ultimate. It had Intel's best mobile chip at the time, the 2.4GHz Core 2 Duo T7700, and 4GB of RAM. All that horsepower helped the HP Pavilion HDX earn a WorldBench 6 Beta 2 score of 86 and generate a frame rate of 109 in our Far Cry gaming tests - a performance that would put many of today's laptop powerhouses to shame.
The HP Pavilion HDX's two-hour, 22-minute battery life was poor for an ordinary laptop but remarkably good for a huge (7kg) desktop-replacement model.
Next page: The PS3 laptop
So that's the fully-released and soon-to-be-launched laptops done with. Let's move on to the designs you're unlikely ever to see in the shops.
Desktop PC modders have switched allegiances to laptops in recent years, with devoted techies fighting it out to build the weirdest custom-built portable computer.
For example, Ben 'Heck' Heckendorn - the modder who created an Xbox 360 laptop with a built-in camera - turned his attention to the PlayStation 3 (PS3) last year, building a laptop using the hardware components of Sony's console.
The PlayStation 3 laptop is based on Sony's original 60GB PS3, but includes a 17in HDTV 720p screen with an HDMI connection, a built-in keyboard and a stereo amplifier. The 7.26kg machine measures 431.8x349.3x76.2mm.
The PS3 laptop is run of the mill compared to this contraption.
Apparently a fully working laptop with USB and Ethernet connectivity, it was developed by a Japanese modder and includes mechanical keys, a wooden space bar and an all-important Morse key over the trackball.
See more designs here.
Apple MacBook Wheel
We can't run an article on design innovation without mentioning Apple and, to be fair, the MacBook Wheel could be the biggest laptop advance of them all.
Apple has replaced the archaic input mechanism of yesteryear - the keyboard - with a sleek, touch-sensitive scroll wheel. The design will make typing a thing of the past, according to The Onion's exclusive video (below), with users able to type messages and search for files using one all-purpose device. "Everything is just a few hundred clicks away," according to an 'Apple exec' in The Onion's video.
Fair enough, the Apple MacBook Wheel is just a spoof, but the other products here can lay claim to being the world's weirdest laptops. But given that the list includes systems that were launched in the last few years, are there any other models that should have made the list? Let us know using the comments section below.