First of all no single thing controls it as its collection of policies which dictates the overall power consumption taking in you have decent efficient radio also. But SetCPU is a must if your rom does not have mCPU performance frequency handling. As you want to setup advance mCPU policies defining the clock frequency when screen is off to the lowest and when its on and if nothing requires resource its then its underclocked. Not taking in your kernel supports OC and has types of pre defined governors as voltage swing can even make it unstable even stall and freeze the device.
The biggest thing to kill battery is the screen so what you might want to have the blacklight intensity low. Far as the connection goes to push out data you can use JD and based on given interval sync data and have connection(wifi+data) disabled when not used which will save more power. Far as memory/resource goes you can also disable services that you never use and set up policies to keep it disabled on boot and could manually be started by user.
As I am using CM7(GB) now
Keep in mind I am using standard stock battery as Mugen Power 1650mAh is out of stock :P but my battery is calibrated. As you can see its collection of things which controls it and not single app or setting.