Have a secondary hard-drive in your laptop/desktop that you don't often use?
hd sleeper is a small, free and open-source utility for Mac OS X 10.6+ that will allow you to quickly put to sleep and wake up your hard-drives.
With many people switching over to SSD these days, I wanted a quick way to put the secondary hard-drive to sleep when not in use, to save energy and create less noise.
hdsleeper is the result, it seems to work decently so I've decided to share it.
Drag the application to your Applications folder
Run, right click on Icon on menubar and select Preferences, set as required.
Use "Unmount" to put hard-drives to sleep, "Mount" to wake up.