If you were paying attention to CES 2013, you may have noticed that one of the more popular items on display was the flexible screens under development by Samsung. As their short video showed, the flexible screen will open the door to some new form factors. Until then, if you want something unique you may have to look for something like the NEC Medias W N-05E. NEC has basically taken two 4.3-inch devices and merged them together with a hinge in the middle. When opened, the device doubles screen real estate while maintaining a small, pocket-able size when folded up.
The screens are supposed to be able to function independently of each other, with separate apps running in each screen, or the two screens can act like one big screen. The device is powered by a 1.5GHz dual-core cpu, 1GB of RAM, 16GB of built-in storage and the ever popular microSD slot for expansion purposes. However, NEC did not include NFC capability in the device. which will run Android 4.1 Jelly Bean.
NTT DoCoMo indicates the device should be available in mid-April. No information on other markets, pricing or a release schedule if it ends up in markets outside of Japan.
source: NTT DoCoMo