If you get all butterfinger-y when you're holding a running hard disk, the I-O Data HTH-USR might just save your ass. It has a 3D G-sensor that can tell if the drive is about to experience a sudden impact, parking the read/write heads and preventing any data damage.
It's about time somebody brought this technology over from hardened laptops which have had this technology for a while now. Available in 400GB and 750GB capacities, the higher-capacity HTH-USR will retail for $766.
HDH-USR, the HDD with a 3D G Sensor [Akihabara News]