I'd prefer something like this: http://www.engadget.com/2009/08/01/urban-mole-robot-could-deliver-your-mail-via-insane-network-of-u/ http://www.engadget.com/20

I'd prefer something like this: http://www.engadget.com/2009/08/01/urban-mole-robot-could-deliver-your-mail-via-insane-network-of-u/ http://www.engadget.com/2009/08/01/urban-mole-robot-could-de... - no noise - no accidents involving people - less energy needed - much simpler / robust construction