Recently my wife was complaining of a sore stomach at around 2am and instead of asking what I could do to help, I darted out of the room and came back with my recording rig and a contact mic (Aqarian Audio H2a-XLR Hydrophone). It turns out her stomach was not upset in a very dramatic fashion in terms of the audio it was producing.
So I slapped the mic on my stomach and realized it was a gold mine. My stomach was not upset at all but it was rumbling up a storm.
While I was at it I put the mic on my chest to grab some heartbeat sounds. If you have a sub woofer take a listen through it because my heart was pounding out the lowend. Strangely about 10 seconds into this clip my heart kind of stutters a bit. Maybe I am going to have to keep tabs on this.
This past weekend some friends came over and one of them is a few months pregnant, so I got out the gear to see if we could hear the babies heartbeat. Sadly the experiment failed as its tiny little heart is not pumping loud enough yet. But later on I did get this recording of crazy belly action later on.