James Randi explains homeopathy.
James Randi breaks down the four rules of homeopathy -- really, they break down all on their lonesome -- and discusses what some commonly-used dilutions really mean.
Summary: You want me to take a pill that contains 1 part in 101500 of the supposed active ingredient? Ri-i-ight.
(Related link: http://www.youtube.com/watch?v=BWE1tH93G9U)