2 cents

Here is my suggestion for the Gulf oil leak (everyone is making one, and yes, it is in the news here as well). What about a freeze lock? It would need a sleeve around the pipe before the break. Pump the sleeve with liquid nitrogen surrounding the pipe, the oil in the pipe cools down and starts to become solid, once it solidifies completely, then the end of the pipe can be cut and refitted. In a pipe the fluid moves fastest in the center and slower near the edges and at almost no speed at all microscopically near the edge because of viscosity. Immobilizing a small layer near the edge effectively shrinks the inside diameter, slowing everything down a bit more and so on. Liquid nitrogen is cheap and they have underwater robots...? Of course it would need to be over a long enough section to hold back the pressure behind it, but if they could just slow it down enough ...