Electronista: While companies such as Hammacher Schlemmer have sold gimmicky portable mixers meant solely for entertainment, the forthcoming Pacemaker by Tonicum may actually be useful for less intensive professional gigs.
Small enough to fit in a pocket, it nevertheless holds 120GB of music, and has essential features such as a crossfader and a touch surface used for controlling elements such as bend and pitch.
There are twin 3.5mm stereo jacks, and the mixer can record directly to a separate hard drive. A black-and-white screen displays necessary track information.
No cost for the unit is available, but it should begin shipping in the fall.