Isn't there a way to get information from HDD's about how long they have operated from when they were manufactured using SMART? Not that anyone keeps those records on hand once the HDD is no longer in their possession, but if you are paranoid, you could start offloading those records every minute to a different server. That way if yours is seized, you could at least know if someone had turned on your HDD's and for how long.

It'd be cool if HDD's/SSD's started compiling rough stats about numbers of reads and writes for this purpose.