Developer: appsolute GmbH
Price: $14.99 Download on the App Store
Karajan and Karajan Beginner are ear training apps from Holger Meyer that are a step above many ear training programs. Beginner is a free lite version of the $14.99 version and has a lot of the features of the original version minus the advanced stages of training.
You can test your ear for prime, major second, perfect fourth and fifth intervals. There are also ear training exercises for chords, scales, pitches and tempos. Unlike many ear training software programs, the timbres to pick from (piano, e piano, acoustic guitar, slapped bass, and organ) are very palatable, especially so for a free app on a phone. The user interface is easy to understand and comes with several options for entering answers including a keyboard. There are also statistics that help track your progress.
Although it is a fairly specialized application, mostly useful for music students, it is a great way to whip your ear into shape even if your just a garage musician. Add up the number of people in cover bands out there playing Freebird who should be training their ears a little better, and you have an app that would benefit the rest of us as well.