Even more spectacular than the Morris worm
At the recent Key Management Summit I was talking with some of the people who had really come for the IEEE Symposium on Massive Storage Systems and Technology about some of the more spectacular security incidents that have affected the Internet. These included things like the Morris worm, the SQL Slammer, and other high-profile incidents. One of the people that I talked to works for CERN, and he told me about a type of incident that they apparently deal with on a routine basis that's a bit more spectacular than any of these security incidents.
In big particle accelerators you apparently get an event called a "magnet quench" now and then. These start when one of the superconducting magnets that controls the accelerator's particle beam develops a glitch. Maybe one of the magnet's superconducting coils gets hit by stray high-energy particles, for example. This can heat the coil to the point where it loses its superconductivity.
These coils can have tens of thousands of Amps running through them. This is OK when they're superconducting, but causes problems when they're not. When the coils lose their superconductivity, resistive heating from the huge amount of current flowing through them makes them even hotter. All of this heat then boils the liquid helium that's cooling the coils, which then vents through the equipment's pressure relief valves in a spectacular way.
Those superconducting coils probably aren't cheap, but I'd guess that the economic damage caused by any of the high-profile security incidents is greater than the cost of repairing the damage from a magnet quench in a big particle accelerator. I'll bet that the magnet quench is more impressive to watch, though.