dmainmon @ instructables.com has build an analog signal graphing project using Arduino Mega 2560 and a 2.8 TFT display. This project is used to display two analog signals as line and bar graphs. Touching the screen pauses the graph and opens a menu to adjust setting for the graphs.
The project uses an Arduino Mega 2560 and UNO R3 2.8 TFT Touch Screen to display two analog signals as line and bar graphs. One signal is a photo resistor and the second is an audio sample from an Adafruit Electret Microphone Amplifier with Adjustable Gain module. The audio signal is graphically displayed twice; once in the center using a line graph and also on the bottom with a bar graph. The top graph represents the photo resistor signal.
Arduino Analog Signal Graphing on a TFT – [Link]