Available on the iTunes App Store
Polynome is an iPhone 4 and later app that allows you to visualize and hear complex rhythm patterns. You can set up to 4 individual rhythms, each being from 1 to 11 beats per measure. You can adjust the tempo (beats per minute) from 20 to 220.
For each line you can set the following:
On or Off
Beats per measure
Note that the first enabled line is what the tempo refers to.
Sound stage - Stereo or Monaural
Stereo sounds pan from left to right.
Color of led
You can add a custom click sound via iTunes file sharing and then use it for one or more lines.
The sound can be theoretically any type, but it is recommended to have it be a 2 channel, 44100 Hz caf file.