List Of Unexplained Sounds
This article provides a list of mysterious or previously unidentified sounds. It includes NOAA sound files that have been sped up by at least 16 times to make them more understandable, shifting the frequencies from infrasound to a range that is easier to hear and analyze.
#6 Actually a really cool list
#19 I remember when I first found out that the Roman statues used to be paint to make them appear lifelike. Creepy.