http://web.media.mit.edu/~monster/blendie/dobson_blendie_small.mov

this is sh_t,

to do this you need
a blender,
a person and
a dimmer (usually used for living room lights.. )

hook the blender up to the dimmer, switch the blender on and you can change the speed with the dimmer control..

in highschool we used to hook up dimmer controls to tubelighting and reduce the power intake to make them flicker.. constantly!