TED Spread
The Treasury/Eurodollar spread is the difference between the yield on the three month U.S. Treasury Bill and the three month Eurodollar LIBOR rate. It is a measure of the premium over ultra-safe U.S. Treasury Bills that banks demand for lending to each other. Normally around 20 to 40 basis points, the TED spread balloooned to nearly 500 basis points in the autumn of 2008 at the height of the panic over the stability of the global financial system.
See also: http://www.econbrowser.com/archives/2008/09/understanding_t.html