DriveSwitch is a simple status bar icon for Mac OS X to spindown or mount a harddisk. I made this for the second harddrive in my MacBook Pro. alt click on the icon, and click settings to change the disk. Usually this is disk1s2, but may be different in your setup. TODO: find an Icon that looks like a harddisk.
rene-dev/DriveSwitch
OS X Menulet to mount/unmount/spindown a HDD in the optical drive bay
Objective-C