Silent Power's tiny computer doesn't even really look like a computer. It looks more like a pot with some strange hedge growing out the top of it. But in fact, the whole package is half computer, half heat sink, with an oversized copper blob on its top side being used to cool the entire machine, allowing it to run without fans. It isn't a weak computer either: though it'll be inside of a small package (just 6.3 inches on its longest side), Silent Power says that it'll include a Core i7 Haswell processor and a discrete graphics card from Nvidia.
The heat sink on top is a metal foam, which isn't a new innovation, but is something you're more likely to read about in a scientific paper than a spec sheet. The Silent Power PC isn't ready to ship just yet though. It's effectively being crowdfunded, with its manufacturer taking preorders for it that will only be filled if it sells 45,000 euro (just over $60,000 USD) worth of machines. If you're in the market for a somewhat nontraditional computer, you can try to get it built over at Silent Power.
Update: A critical analysis from Hack A Day points out that potential buyers should be skeptical of Silent Power's claims. As Hack A Day notes, Silent Power originally posted their project to Indiegogo, only to pull it down inexplicably. Now the company is asking for funds independently through PayPal, but its account was just frozen. Funder beware.