X Lossless Decoder (XLD) is the tool for Mac OS X that is able to decode the various 'lossless' formats. The supported audio files can be splitted into some tracks with cue sheet when decoding. It works on Mac OS X 10.3 and later.
XLD supports the following formats:
Monkey's Audio (.ape)
Apple Lossless (.m4a) [10.4 only]
AIFF, WAV, etc
Currently you can choose output format from WAVE,AIFF and Raw PCM. In addition, you can choose Ogg Vorbis, MPEG-4 AAC, MP3 (lame) and Apple Lossless in the GUI version.