X Lossless Decoder(XLD) is a tool for Mac OS X that is able to decode/convert/play various 'lossless' audio files.

WavePad works as a wav or mp3 editor, but it also supports a number of other file formats including vox, gsm, wma, real audio, au, aif, flac, ogg, and more.

Ventrilo (Vent) is a VoIP software that includes text chat.