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.

Asus dual-screen laptop

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