The eMark Super Mobile Keyboard is marketed as the world's thinnest keyboard and just so happens to be spill-resistant—no more worrying about a cup of joe (or, mayhap, other liquid-like substances) muddying up the keys. From Japanese company Kimura Metal, the keyboard measures only 1mm, or about 0.04-inches. The USB keyboard has a retractable cable and comes in both white and black. Since it's so thin, it's possible to wrap it much like a Fruit Roll-Up. It's due to hit Japan later this month for around $256.
World's thinnest waterproof keyboard, if you wil [Digital World Tokyo]
Kimura Metal Home Page (in Japanese) [Kimura Metal]