Electronic paper (or e-paper) is a collective name for display technologies that offer paper-like performance - high display clarity and sunlight readability, and all that with very low power consumption (usually ePaper displays do not require any power while the image is not changing).
ePaper displays are found in many devices (most people will associate ePaper displays with e-readers such as Amazon's Kindle). ePaper displays are slowly entering the consumer wearable market, mostly for smartwatches and fitness bands.
SQFMI's is an open source (hardware and software) smartwatch that features a small 200x200 E Ink display and a low-power dual-core chipset (ESP32-S) - the watch should last for about 2 weeks on a single charge.
You can download all the documentation for Watchy on Github to produce your own device, or buy an assembled one for $55 (it will soon be available through SQFMI's web store).
The Fossil Hybrid Smartwatch HR (Heart Rate) is a smartwatch that features mechanical hands placed on top of a 1.06" E Ink display. The watch tracks your heart rate, activity and sleep and provides in-depth wellness stats and lasts for two weeks between charges.
The Study Watch by Verily Life Sciences (ex Google-X division) is a health-tracking smartwatch that features an always-on E Ink display, environmental and physiological sensors and long-lasting battery.
The study watch will used in observational health studies - it will not be sold to consumers.
POP-I's E Ink backpacks use an E Ink panel on the back. You can customize the image via an application on your phone (iOS or Android). There are several backpacks available, with a display size of either 4.7" or 10" (HD). The bags themselves are made from either canvas or leather.
POP-I said it was to ship those bags at the summer of 2017, for $99 to $399.
Sony's FES Watch U is the successor to the popular (in Japan) Sony FES watch. This is an E Ink watch that also has E Ink on the wrist-band, so you can change the design at will. There are 12 basic designs, but this is software based and will increase as Sony makes available an iOS companion application.
The Calendar Watch is a simple smartwatch that uses an E Ink display below analog clock hands to show what parts of the day are busy. The watch is controlled by your smartphone - both the calendar display and the clock itself.
The Withings Go is a small and light fitness tracker that can be worn as a wristband or clipped to a clothing, and it features a circular E Ink display. The Go monitors activity and sleep, is water resistant (50 meters) and can monitor swim strokes.
The Withing Go started shipping in 2016, for around $70. It is no longer available.