"Polyrhythm is the simultaneous use of two or more conflicting rhythms, that are not readily perceived as deriving from one another, or as simple manifestations of the same meter." - New Harvard Dictionary of Music.
This application teaches you polyrhythms. You can hear what they sound like and the application provides a score based on how well you perform them.
The polyrhythm is visualised using the beat circle shown at the centre of the screen. This circle contains two types of beats. The beats are represented by coloured shapes placed along the circle's circumference, and are colour coded green or blue. When the green beat is heard you tap the screen where indicated, and likewise when the blue beat is heard, tap the screen where indicated. When you are happy you understand the polyrhythm you just stop tapping and the application will tell you how well you did.
This application uses Adobe Air. This version is limited to a 4 beat subdivision, so you can do up to 4:4. The full version allows up to 8:8.