Check out this really cool concept device called the DIY Player by a designer name Shao Wen. This device has detachable modules which can change the function with each new module snapped on. For example snap the media controller on and the device turns into a PMP, snap a keyboard on and the device turns into a mobile phone or snap a lens on and you have a digital camera and the possibilities are endless.
It can also be transformed into a e-Book Reader, Recorder, a Mini Hard Disk, Mini Speaker, GPS, Alarm Clock or even a remote controller. Another great concept from another great designer, too bad it will never hit the shelves, or prove me wrong!!