I have used many inventive ways of destroying hard drives.
I call BS on the hammer on the platters method. You just get a frigging huge "WHANGGGG" with metal platters if you hit it with a hammer. When I tried that method at work, after the first strike I moved outside and repeatedly tried to smash the platters. Not only did it not work, the racket attracted the landlord who was wondering WTH was causing the noise penetrating his soundproofed office. After having it explained, he suggested another method.
I can certify that running over hard drive platters with a tank works acceptably well as a secure destruction method, however it's slow and requires access to machinery difficult to get hold of. Running over them with one of those press things that roadworks use also works pretty well, and a pack of beer can unlock the possibility of adding the mangled remains to the foundations of the road. Again though, difficult for some people and ultimately these measures are only really suitable for small scale disposals since dissembling the drives and affording the beer required is beyond most of us for several thousand drives.
The solution is a four phase process.
1) Multi layer writing random bits all over the drive. That alone should make life interesting for people trying to recover stuff from it.
2) individual degaussing of each drive to 4X the manufacturers guideline for utter destruction of the drive. However, there is some possibility that two bytes of data remain on the drive connected to each other, and you may be able to recover more with appropriate data recovery stuff. So...
3) Physical destruction, courtesy of an external supplier which reduces the drives to chunks of mangled scrap. That would mean you'd need a clean room environment to get anything off of the drives, and in combination with stages one and two, I think it's secure enough to let off site for the trip to...
4) Being melted down in a furnace. Apparently they contain a fair amount of valuable metal. Which is fair enough really, lots more aluminium in a HDD than a drink can and it's reasonably secure as destruction methods go.
I'm pretty confident that the drives I have dealt with are well beyond recovery, and won't be seen in the newspapers in these sort of stories! The worst case scenario is that the van gets hijacked after 3, and I think I could live with "only" the previous 3 levels of destruction.