Interesting article on the New Scientist site called "13 things that do not make sense" which list 13 scientific phenomena that have no scientific explanation. It covers things like the placebo effect, homeopathy (though it points out only the mentioned study has had results as reported - I wonder if it is the same one highlighted in the Horizon documentary on homeopathy?) the possibilty of another large planet in our solar system, the ever accelerating Pioneer spacecraft, anomalous results from the Viking mission to Mars and cosmic rays that break the laws of relativity.
While on the subject of relativity - here's an explanation of Einstein's Theory Of Relativity using words of four letters or less. It's still just as difficult to understand but the words are easier to read! ;)
via linkfilter and HyperSloth