Fuel Cell Handsets From NEC
NEC's concept cellphone uses an alternative fuel that unintentionally or intentionally makes said cellphone resemble a lighter flask. We don't know if fuel cell technology of this size already exists but the resulting product looks dangerous.
It is apparently touch controlled and has a transparent to provide a rather cheeky battery indicator. The liquid drains while the phone is using up power. No details have been published besides the ones you can glean from the picture.