ICE is also an acronym for in-circuit-emulator.
An in-circuit emulator, typically for an IC, usually consists of a box with lots of microprocessors in it, a data cable on one side for connecting to a computer, and a cable on the other side that ends in a plastic block with pins on it the same shape as the IC being emulated. An application runs on the computer, so the ICE can be reprogrammed, usually breakpoints can be added, and usually a dump of all the registers can be performed at any time too. Other, more sophisticated features are available on more expensive ICEs, but of course you have to pay for extra functionality. The use of an ICE in the development of electronic circuits greatly facilitates debugging because the code can be traced much more easily.