REMOTE CONTROL--In addition to denying access to your files by encrypting, you might want to *change* them in some way *after* your computer has been seized/stolen. Pagers are cheap. They can be pinged no matter where they are located in their service area. They can be accessed from any phone (even a jailhouse payphone). And they are small enough to be wired into your computer. It souldn't be too difficult to fix it so your computer can read transmitted numbers from the pager's memory. Code numbers could be used to tell your computer to take various actions. Depending upon your circumstances, you could tell your computer to decrypt this or that set of files, to reformat the hard drive, to fry the CPU, etc.
This would of course assume that the police were silly enough to use the disk and such from your machine in your machine. From my experience w/ Mentor and Erik Blookaxe during Operation Sun Devil this is not very realistic. As I understand it they took the floppies and the hard drives out of the original machines and used them on their own. This was in case their was any 'time-bombs' installed. Another aspect would be that the machine would have to be turned on. Also it would only work once. Thereafter they would either examine the equipment in a Farady Cage or else start doing pager rental scans prior to seizure.
LITTLE BROTHER INSIDE--Even better than a pager, would be a cell phone. It would be more expensive, but also more versatile. In addition to giving instructions to your computer, a cell phone could be used to *eavesdrop* on the location where your computer is being held. By disabling the ringer and remounting the mouthpiece, you could surreptitiously call your computer, any time, from any phone and monitor conversations in the area. (To paraphrase an old military curse, "bug the bugging buggers.") As long as the computer is plugged in, the cell phones batteries will continue to be topped off. (For the truly thorough privacy advocate, a GPS unit could be hooked into the cell phone to give you its location.)
There is a move here in Austin, TX to put GPS rcvrs. in our police cars and then transmit the data back to base over their laptop channels.