LG's Rolly Keyboard is portable and can connect to your smartphone and tablet via bluetooth.
It's made of durable polycarbonate and ABS plastic. To use it you simply unroll it and connect it via bluetooth to up to 2 devices at the same time. It's powered by 1 x AAA battery and can last up to 3 months of average use. The keys are about 17mm which is a bit smaller than a standard keyboard that has 18mm keys.