I've gotten lots of tips on recovering data. Everything from changing the orientation of the hard disk (make it vertical, its narrow sides pointing up and down). Manually spin the disk, etc.
Tapping/rapping on the drive with your knuckle or the handle of a screwdriver might get the drive to engage; just don't whack it too hard.
Also- as crazy as this sounds, putting the drive in your freezer for a few hours might get it functioning long enough to copy off the data:
- Remove the drive and place it in an anti-static bag.
- Place that bag inside two zip-lock freezer bags; suck as much air out of the bags as possible.
- Leave the drive in the freezer for at least a few hours.
- With the drive still in the baggies (keeps the cold in longer), hook the drive back up to the computer and power up.
If the drive comes up, you may only have about 20-30 minutes before it heats up and stops working again, so get copying quickly. I'd suggest you start by copying your most critical data first just in case the drive dies during the copy process.
I performed the above proceedure on a client's drive last week, and it worked.