I didn't want to spend $25ish for one of those drive suspension devices, would like something like a Smart Drive, but $70 is way out of my budget to quiet a drive (hell you can almost buy a new drive for that much.)
This mod would have been more complex if I had a 2 harddrive system, but with only one drive it was really easy.
What I did was to take some 1" foam rubber, and some elastic strapping and installed my harddrive onto a foam bed. Cost me all of $2.00 and took about 5 minutes to remount my harddrive.
The idle noise of the Barracuda IV 80GB drive has dropped audibly by a large margin. I can still hear it seek/read, but it is only a fraction as loud as it was before.
A very quick and extremely worthwhile quieting modification.
Oh, and it only seemed to raise my drive temp by 1 to 2 degrees Celsius.
Click here for a full size picture.
Nothing earth shattering or particularly clever, but it works darned well.