http://www.shomer-tec.com/site/product.cfm?id=99884ADD-A1D1-2490-B63997E59A7F5DAF
 ie. Does it actually have any effect?  At what range?  How audible is
it?

You might enjoy researching devices which generate "infrasonic" or
"subsonic" sound.

Many years ago the U.S. military studied the medical effects of
subsonic sound.  A device hauled on a trailer behind a truck,
generates subsonic sound of sufficient intensity to damage and destroy
organs in the abdominal cavity ? presumably of enemy soldiers,
although the beam is so poorly focused that everyone in the vicinity
gets a big dose.  At lower intensities these subsonic vibrations can
be used to stimulate the abdominal organs, creating a feeling of
intense nausea.

Before you purchase or construct such a device to exact revenge on
your irritating neighbors, however, you might consider your potential
exposure to lawsuits.

This article may be of interest:

http://www.forteantimes.com/articles/153_sonicweapons.shtml