@Hodgkinson:
There are plenty of programs on Aminet to do this. The one I use is Sleeper 2.0 which is nicely configurable by icon tooltypes.
It starts separate "sleep" timers on the device IDs you select. The timer is reset every time that device ID is accessed.
@Piru:
The regular head seeking is probably thermal recalibration, which the drive automatically does. The purpose is that as the temperature of the platters changes, the metal expands or contracts slightly, therefore causing tracks on the disk to become further apart or closer together. The drive recalibrates itself regularly so that it knows the distance between tracks exactly.
As for drives automatically spinning down, personally I've never seen one do it by itself, though I'm not surprised if it's been an automatic power saving feature added into the firmware of newer drives. Reading through manufacturer's docs as suggested is probably the best way to find out for sure.
