An inexpensive party light. Basicly it would screw into any light socket, and would focus the light into a beam, like a spot or pin light. Then, it would nave a small frame and motor built in the end where you could put in a gobo that the motor would spin. The light and motor would sell for about $15-$20, and the gobos would vary in price depending on if it had colored gels or not. This would work well with over head lights pointing down, track lighting, or regular lamps that point straight up. If those sell well, future models could include an on-off switch for the motor. A speed dial for the motor. Or even sound control (varying speed, and direction change based on the beat). I think they would sell well in head shops and would be nice inexpensive accents for parties.
The gobos them selfs could be any size, as the clip in on the end. The only limit would be weight. So they could also have mirrors and lenses for further effects.
So, who want's to go into business with me to make and sell these? :-)