When E-ink unveiled its Spectra screens in 2013, the cutting edge 3-color epaper displays were only sold in the e-shelf label market.
With exactly three colors (black, white, and red) and no shades of gray or red, these screens wouldn't have been much use for ereaders (not unless you wanted to forgo images). But it would be great to use the screens in DIY projects, and now we can.
With screen resolutions of 400 x 300 and 206 x 128, the screens could be used for smart labels, Internet of Things, secondary screens on mobile devices, or to display info where permanence is more important than resolution or color. One popular use for screens this size are as accessories to Raspberry Pi and other SBCs.
If you get one you will also need a gen-2 extension kit, as the earlier kits aren't designed to work with either a Spectra or an Aurora E-ink screen. You can find both the new screens and the extension kit at Digi-Key.