For those of us who like to control the speeds of our fans via hardware, Scythe recently unleashed a product that is sure to please. Dubbed the "Kaze Master VFD display fan controller", this interesting thing will fit in your standard 5.25" or 3.5" drive bay. The 5.25" version can handle 4 fans, assuming none of them require a current of more than 1A (12V). The 3.5" version can handle two fans of the same strength. This controller allows fans to run with between 3.7V(±10%) and 12V(±10%) of current, and also has a switch that turns them off completely. You can get them in black or silver for roughly $40.

The 5.25" version is here, and the 3.5" version is here.