Are you tone deaf or do you have bad taste in music? US medical student Jake Mandell has developed an online test to determine if it's the former. He takes up the story:
"While working at the music and neuroimaging lab at Beth Israel/Harvard Medical School in Boston, I developed a quick online way to screen for the tonedeafness. It actually turned out to be a pretty good test to check for overall pitch perception ability. The test is purposefully made very hard, so excellent musicians rarely score above 80% correct." Try it here.
(Postscript: I scored 78% but since I struggle to tune a guitar I'm not reading much into that.)