I have implemented a SOC (State of Charge) meter for the Nissan Leaf. Many thanks to garygid and others from the MyNissanLeaf forums, for their help in decoding the Leaf CAN bus messages, and figuring out the pinouts.
The top line shows the SOC%, raw SOC value, and number of charge bars displayed in the dash.
The second line shows battery pack voltage and current in amps.
The schematic shows how to implement the entire circuit, without using the Olimex AT90CAN128 breakout board.
My original intent was to make a small PCB that directly attached to the LCD, and put it into a small case, but I never got it past the breadboard stage. Unfortunately, I have gotten busy with other projects, so I am probably not going to do further development on this device nor finish the PCB layout, unless there is a large amount of interest. However, feel free to adapt it as you wish for your own CAN bus projects. Do bear in mind, however, that the design is licensed via the GPL, so if you use it for a commercial project, you must openly share your design.