The icelandic tug
Have you seen that Top Gear episode where they drive to the North Pole in a Toyota Hilux? I've watched it several times and am intrigued by the way that the truck is pulled out of a crevasse by the Icelandic snow driving experts. There isn't enough friction for one truck to pull the other so they attach an elastic rope between the trucks with a lot of slack in it. The pulling truck then drives off as quickly as possible. When the truck is travelling at quite a speed the rope becomes tight and pulls the other truck out of the hole. So there isn't enough friction for one truck to pull the other but there is enough for one truck to accelerate on it's own. When the rope comes tight the force exerted is pretty high. You may have used the same principle to break a piece of string by holding it slack between your hands then snapping them open. The force exerted would be even higher with a non elastic rope but would almost certainly snap it, the elastic rope not only reduces the force but gives time for the second truck to start moving without stopping the front one. I have often thought of recreating this in interactive physics and today I got round to doing it. I would have posted a link to the actual video but I couldn't find this bit in any of the clips, obviously no one else thought this bit was interesting, that or I dreamt the whole thing up.