Dead Channel

"The sky above the port was the color of television, tuned to a dead channel."

William Gibson - Neuromancer

I've always enjoyed metaphors that are modern. He could have so easily said that it was the color of glacial ice or as grey as a dark sky before a hurricane. In either case he could have set the same foreboding mood. Considering the genre, sci-fi, the "dead channel" seems to invoke perfectly both the description of the sky, the impending doom or depression, as well as hit on the fact that what the reader is about to read is fresh, modern and out of the ordinary.