There's a lot to explore with Push right out of the box - use it to play instruments, sequence beats, tweak effects, and more. If you want to go even deeper, Push also plays well with Max for Live, which offers virtually limitless possibilities for its functions. To demonstrate this, Cycling '74 have created a "frequency mixer" device which is controlled by the pads on Push:
Frequency Mixer for Push and Max for Live
This device is available as a free download from Cycling '74, as part of a tutorial on programming Push with Max for Live. If you want to go further under the hood, the frequency mixer makes an excellent tool for reverse-engineering working with Push and Max for Live, and the tutorial provides step-by-step instructions for how to do this.