VoodooHDA is an alternate driver for High Definition Audio based Sound Cards. It's made as a replacement for AppleHDA.kext driver, and based on a BSD Driver.
VoodooPS2Controller is driver for PS2 devices such as Keyboards, Mice and Trackpads, the PS2 interface being very used in PCs but quite rare in Macs. It's a replacement for ApplePS2Controller.kext, it adds double finger scroll capability for trackpads. It allows to get rid of AppleACPIPS2Nub.kext, required by ApplePS2Controller.