I've generated 2 new versions of Fan Control, one for the Intel-based iMacs and one for the MacBook/MacBook Pro which has some extended control capabilities over the original Lobotomo Fan Control version. For screenshots and (free) downloads (with source code) see:

iMac Fan Control

Extended MacBook/MacBook Pro Fan Control

The iMac version allows separate sensors to drive the control of each of its 3 fans and the extended MacBook/MacBook Pro version allows fan-control via the CPU and/or GPU temperatures (useful if you play games on your laptop). There are also some other minor enhancements (see the ReadMe files).

I've also tried to make it easy to adapt the source code for other systems ... e.g., a version for the Mac Pro that uses different sensors to control different fans (or groups of fans).

Hope these are useful to others.