Oh, I wasn't meaning Pulse Width Modulation in a bad way, as it is currently the most effective speed control for fans.
RadioShack has a PWM kit which we can bum the design off of and make our own.
To do this, we need to gain extensive knowledge of PCI; ISA is not even on many of the mobo's that modders use. I have found two sites...
Technical Overview (very informative)
Industry Standards Organization for PCI architecture