I thought I might take a look at the use of color in this novel. After all, the story has a lot of powerful imagery, and it was originally meant to be a "computer-generated graphic novel", so the design of the imagery must have demanded a lot of attention. Even the title of the book, "Snow Crash," is a term with some intrinsic color qualities. A snow crash displays "white noise", "a pattern of black-and-white pixels" (73-74). The black-and-white of the snow crash is a very bad thing: it's associated with nonsense, an extremely primitive fault with a machine. If you see a snow crash, you've witnessed a "system crash... at such a fundamental level" that the graphics output fails (42). It's both menacing and something to scoff at, a simple failure; a properly-protected computer shouldn't suffer a snow crash, but if it has been infected with a virus, it might.
There are also the black-and-white avatars, which tend to draw suspicion and distaste from everyone else. These are "persons who are accessing the Metaverse through cheap public terminals... a lot of whom are run-of-the-mill psycho fans" (41). The grainy black-and-white avatars represent a sort of lower class of Metaverse user, and that lower class apparently consists of generic yet obnoxious characters. "I can't believe you took a hypercard from a black-and-white person," Hiro says to Da5id, implying that Da5id would have to be very stupid to do that. It implies that black-and-white people are dangerously unaccountable, and consequently something to distrust or scorn. This is pretty consistent with the black-and-white of the snow crash: in both cases, the grainy mixture of black and white is associated with something both mundane and dangerous.
However, black by itself, or rather, black with itself, is associated with power within the novel. The uniform Hiro wears when he is The Deliverator is "black as activated charcoal" (1), making him "a grim vision in ninja black" (5), and "his car is an invisible black lozenge, just a dark place that reflects... the loglo" (7). The equipment of the Deliverator is associated with efficiency, danger, and power. He is stealthy, very fast, and wields tools that are immensely powerful, and all of these tools are black. Similarly, the Metaverse's number one hacker hangout is "a squat black pyramid" with "a matte black hemisphere... set in the front wall" - "THE BLACK SUN" (39-40). It's another case of black-on-black, a combination that (unlike black-and-white) is associated with the few most powerful, most dangerous individuals in the Metaverse.
Then there are the colors of advertisements and other businesses. The Kourier service wears a combination of "orange and blue" (13), and the Enforcers uniform is an "acid green uniform" (122). Mr. Lee's Greater Hong Kong, one of the safest parts of town, is signified by "a green-and-blue sign, soothing and calm in a glare-torn franchise ghetto" (83). The various franchises, and their meaning to the main characters especially, are reflected in the colors they choose for their advertising. Green is security; blue is calm; and orange is flashy but still hip when combined with blue. On the contrary, "cheap, nasty franchises all tend to adopt logos with a lot of bright, hideous yellow in them" (145). These bright, ugly logos are like "radioactive urine" (145) â€“ associated with the disgusting human waste, and probably something that would be dangerous to be exposed to. In other words, all kinds of bright colors are associated with different franchises, but the colors used tend to say something useful about that franchise. This view is both somewhat anticorporate (the distaste for certain franchises) and simultaneously rooted in the kind of psychology that corporate consumerism requires (the association of colors with brands, with the hope that brands can identify themselves as high-quality simply by choosing the right colors).
Of course, even the colored uniform of of the couriers, "fly as it may be", is not always advantageous (259). Even Y.T., who's normally a very brightly-colored person, between her blond hair and the Kourier uniform, resorts to becoming a "black angel" when it comes down to dangerous business (259). This is when the power-of-the-hackers black convention meets the bright-franchise-colors convention: when Y.T. is working for her franchise, she uses the colors, but when she wants power she reverts her clothing to black.
So throughout the book, lots of colors have pretty strong associations. Black-and-white noise is cheap, mundane, yet dangerous; yellow is disgusting and unhealthy; green is security, and blue is placidity. And of course, though I haven't discussed it here, red is danger. These associations mostly hold pretty consistently throughout the novel, which both makes it powerful as a visual experience and acts as a subtle but defining feature of the corporately-defined system of "government" and lifestyle that is at the core of the novel.