Just read the article, "Flashing light keeps racoons out" in Farm Show, Vol 34, No 5, 2010. This guy was tired of racoons getting his sweet corn, so he hung a burnt out flourescent tube on his electric fence with two copper hooks (one on the hot wire and the other on a post to ground) so that it flashes everytime a surge goes through (and it doesn't reduce the surge). The light will flash, even if it is burnt out, because of the mercury vapor in it.
Police line, do not cross. Well, this tiny ad can go through: