While preparing for my Veloster proximity sensor project, I found these great OLED displays on eBay. They are monochrome 128x32, self-illuminated (OLED), graphical displays with a convenient serial I2C-ish interface and only cost about $4. The only downside is they have a 14-pin flex connector and require some external passives, so connecting to them is a challenge. The first one I used, I hand-soldered 30AWG wire to the flex connector, which was not easy (wiring visible on the right in this picture).
The entire board is about the same size as the display, so the flex connector can fold over and sandwich the two together into a very small package. After getting the boards working, I wrote a piece of code that implements and variety of methods of displaying data, including bar graphs, moving time plots, and multiple digit sizes. The framework code also has a 5x8 pixel font included. At this point, the only real use I've put these to was to test out a new display layout for my Veloster proximity sensors before installing the update in the car. Here's the framework and the display test as an example. This board is available open-source on OSHPark under my profile here