has a few hard drive fans.
JUST COOLER HD-200
and JUST COOLER HD-100
are my favorites they promote AIR FLOW. It taking the blowing cold air onto the drive, and pushing the hot air way. Mind you, you might want to have some sort out take in the rear of your case.
The Just Cooler HD-600
are good at removing the hot air, but there is little cool air coming in to replace it. So I would do with some thing like the Just Cooler HD-815
, And maybe a front case fan to improve air flow.
Failing that, you don't mind modding your PC, install some front fan in front of your hard drives.
Also, if you have the space to do it inside your case, leave a spare drive bay free between your hard drives.
To me, keeping a hard drive cool is not just about removing the hot air, but making sure there is some cooler air coming in too.