This is a one dimensional gesture recorder written in processing. A longer description can be found here http://whichlight.com/blog/innovative-user-interfaces-for-the-android-using-processing/ which includes a browser based demo.
I wrote this as an interface to produce looped patterns from a recorded gesture. When you touch the screen record begins and when you let go recording stops, and then loops.
The values of the loop can be hooked into anything that can take a parameter from 0 to 255, so visualizations, LEDs, or sounds for example. The range of values can be changed, I just used 0 to 255 because I wrote this app to control PWM on the Arduino.
This Processing code can also be run in the browser, using processingjs. So from a codebase with really only one small change (see the blog post linked above) you can have an application running as a desktop app, an Android app, and a web app.