One of the problems I had when I was learning to play and read music was separating out the notes from the rhythm. My music teacher taught us to read notes and then we just had to struggle through sheet music until we got it to sound right. We never really learned to count beats, pauses and rhythms outside of copious amounts of practice and trial and error.
This app comes along and it's basically everything I ever wanted, and very simply constructed. The user interface is simply a metronome, a drum and two measures of music with a time signature. The object is to practice just the rhythm (as separate from the notes) by tapping the drum at the correct time when each note should be played.
The app goes from extremely easy, to incredibly "OH MY! HOW AM I EVER GOING TO GET THIS RIGHT?" hard. It has more than 200 rhythmic exercises, at the end of which you will find yourself able to read rhythm. In addition to the exercises, each one can be changed settings-wise to be a different tempo, or to switch tempos mid-exercise, or any combination of rhythmic mind-twists you can imagine. There's also a training option, for advanced students to listen to a rhythm, after which you write out what it would look like on paper. This is in addition to numerous other options that help the student get the app to look, feel and sound comfortable to practice on. This is a fantastic application and an absolute MUST for any music student.
Requires iOS 5.1.1 or later. Compatible with iPhone, iPad, and iPod touch.