Artist Tauba Auberbach produced this recently:
It's called RGB Colourspace Atlas, and is a physical, printed book of what it implies is the whole RGB colour space.
Is there an existing commercially available ink set that could print something like this? Naturally, CMYK printers couldn't do it because they don't cover the full RGB gamut - they couldn't reach the pure reds, greens and blues. And for spot colours, mixing and blending them is a Bad Idea - not what they're normally designed for - so it's hard to see how they could be used in the complex hue gradients.
Could a hexachrome (CMYKOG, Cyan/Magenta/Yellow/Black/Orange/Green) ink set manage this? Or CMYKRB (.../Red/Blue)? Or anything else?
(Bonus points if anyone somehow knows how this exact book was printed, and hat tip to blog Flowing Data)
Edit: just saw these after DA01 and Brenden's answers, which suggests that Hexachrome gets close to the sRGB gamut but doesn't reach all the blues and doesn't quite reach all the greens:
...and this which suggests HP Indichrome 6-colour doesn't reach all the reds and blues, and quite a lot on the greens (so you'd expect Indichrome Plus to get close to, but not quite reach, the RGB greens):