Yahoo Group for discussion of mysterious hums.

Discussion of research into the physics behind mysterious sounds resembling cannon fire, heard at Barisal, India, and other locations around the world.

Account of the legends and modern accounts of the mysterious sounds heard in Moodus, Connecticut.

Article about the Moodus (Connecticut) noises and the findings of recent investigations that linked these noises with seismic activity.

About.com page gathers together information about mysterious booms, persistent hums, and underground rumblings that defy explanation. Includes audio clips.