Nordic Hardware found details about Zalman's new universal PWM fan controller. This device is designed to be used with your 4-pin CPU fan and can control the RPM of the fan between 25% and 100%. It's a standalone version of the fan controller that shipped with the Zalman CNPS10X series coolers. Pricing and availability is unknown.
The user can either let the controller handle the fan speed at three different settings, or simply set the speed using the control wheel. The unit measures 55 (L) x 24 (B) x 13.5 (H) mm and use a 4-pin fan connector to connect to the motherboard and then to to the fan.