Sites in China and eBay sell an ESP8266 module with 4MB flash and a build-in 0.91″ monochrome OLED display and a rechargeable battery port.
The display is a 128×32 pixel display connected via an SSD1306 controller.
It took me a while to figure out how to get the display to work – the Chinese sellers provide a rubbish demo script that uses the wrong pins for the I2C interface to the display controller.
The following pins and library combination works well:
U8g2 library: https://github.com/olikraus/u8g2
Data= pin 2
Clock= pin 14
Reset= pin 4
A demo program is available here: ESP8266_LCD_Demo
As often, the board requires additional USB UART drivers.
I found suitable drivers for my Mac here – they also offer Windows and linux drivers:
The antenna gain seems to be quite poor – I noticed the module loses connection to my AP about at half the distance that my ESP8266-12 or ESP8266-01 modules tolerate.
I successfully managed to run OTA updatable code (see example).
The board layout is a bit unfortunate as so far as the micro USB connector is mounted on the top, protruding in height above the display, which will not allow to mount the module flush against the top of a case.
Two buttons (reset and GPIO01) allow to invoke flash mode and reset the device, which comes in handy during development.
The pins are labelled both on the front and back side of the board.
At time of writing, the board can be bought between $9 and $12 from Chinese sellers and for $15-$20 from Western distributors. The ones I bought came with a plastic box, a battery cable and connector and pin headers (not soldered)