Can I completely turn off the fans on a MacBook Pro (0 RPM)
Disabling the fans is not recommended but appears possible through the software below:


  smc-command
  
  This tool will allow you to write values to the SMC which could irreversably damage your computer.
  
  ...
  
  This program will allow you to read and write values to the SMC using the AppleSMC kernel
  extension.  The purpose of this is to show how to talk to the controller.


smcFanControl is a graphical interface for sic-command with additional safely limits:


  smcFanControl
  
  smcFanControl lets the user set a minimum speed for built-in fans. It allows you to increase your minimum fan speed to make your Intel Mac run cooler. In order to not damage your machine, smcFanControl does not let you set a minimum speed to a value below Apple's defaults.


Being open source, you could remove the minimum limits imposed by smcFanControl.