How strong is the magnetic field produced by the human body? I have researched the question but all I find is how strong does a magnetic field have to be to kill a human.
[Physics] How strong is the magnetic fields generated in the human body
biophysicselectromagnetism
Related Solutions
There seem to be a lot of human body mechanical models, such as this one: 
As for applications, I have heard that sub-audio frequency vibrations have been considered as nonlethal weapons for riot control.
Addendum:
Guys, stop upvoting this. The image was not composed by me. I found it so long ago there's no chance to find the original source. Google reverse image search says it might be newbedev.com. In the "related images" section there are other similar interesting sketches on human resonant frequency.
The MET (Metabolic Equivalent Task) readout on your gym equipment is your body doing 1Kcal/kg/h = 4184 J/kg/h and can be reasonably accurately measured by how much oxygen a test victim uses.
Sitting still is roughly 1 met and cycling at 100 Watts is around 5.5 Mets.
So taking a man of 75kg, cycling at 100Watts (100J/s) he is having to do 5.5 * 4184 * 75 / 3600s = 480Watts so an efficency of 20%
Remember though that the person is spending 80-100Watts just staying alive doing nothing - unlike your car. There is an interesting experimental fit to how much energy you need to just stay alive, calculated about 100 years ago, the Harris-Benedict equation
Best Answer
Neuromagnetic signals are of the order of 50 to 500 femtoteslas in the brain. (Measured by a SQUID). Split the difference, say 300 fT.
Now you have to guesstimate how much output there is from ordinary cells and their connections.
Say 1/10th of what braincells have, then deduct the 1.4 kg of the highly connected braincells.
Average body weight say 90 kg, so you have (1.4 × 300 fT + 88.6 × 30 fT) and you have a 420 + 2658 = 3000 fT magnetic field.
Is this a very rough (probably wrong) estimate. Yes