MonkeyApp

Monkey’s Audio is a fast and easy way to compress digital music. Unlike traditional methods such as mp3, ogg, or wma that permanently discard quality to save space, Monkey’s Audio only makes perfect, bit-for-bit copies of your music.

That means it always sounds perfect – exactly the same as the original. Even though the sound is perfect, it still saves a lot of space (think of it as a beefed-up Winzip™ your music).