Here, Here, I agree. Keep the governmants away from the tractors!!! I am from Canada where we are still trying to fight the gun registry thing. The last thing we need is to register our tractors. Government registry doesn't help with any illegal activity. Cars have been register for decades yet there is still car theift. Matter of fact there are a lot of people that have got rich making alarms.
Use common sense, keep track of your serial numbers, and store them in a secure place.
And yes post your serial # here if your tractor gets stollen and if anyone finds it they should tell you and contact the authorities (beating the thief comes to mind too, but you had better just call the authorities)