Or similar:
http://en.wikipedia.org/wiki/Beam-powered_propulsion
http://www.nasa.gov/vision/universe/...m/magbeam.html (Although, I would hate to think what would happen if the receiver "broke down" or something...)
When I was young, I thought it would be "neat" to be able to create miniature black holes and use the gravitational force contained to propel a craft. Of course, this was before I knew it wasn't a "hole" but just a collapsed star.
