I've applied a desaturation filter to a number of websites. The Register for example:

  body {
      /* A little less bloody red, eh? */
      filter: saturate(33%);
  }

(Via the Stylus CSS manager extension.)

I also browse extensively on an e-ink (monochrome) tablet, and find that the lack of high-saturation colour is very welcome. I suspect that even colour-based e-ink displays, given their muted pastel palette, might also be an improvement in general.

Edit: That's Stylus, not Stylish, as I'd initially written, Which has Gone To The Dark Side.

Interesting. Stylish looks like malware tho.

Good catch. I'd meant Stylus, though I keep getting the two confused as I'd initially relied on Stylish.

Corrected above.