A free and open source cross-platform multimedia player and framework that plays most multimedia files as well as DVD, Audio CD, VCD, and various streaming protocols.
www.videolan.org/vlc/
Upload your sound file and media.io will convert it immediately. Supports about 50 audio file formats (mp3, wma, wav, ra, m4a, mp4, flac, au, aiff, ogg, asf, gsm, etc.).
media.io
Download audio codecs, video codecs, codec packs and tools, FFDShow MPEG-4 Video Decoder, XP Codec Pack, XviD Codec, AC3 Filter, VideoLAN, LAME MP3 Encoder, and more.
www.codecs.com
A free open source easy-to-use and multilingual audio editor and recorder for Windows, Mac OSX, GNU/Linux and other operating systems. Record live audio, convert, edit, cut, copy, splice or mix Ogg Vorbis, MP3, WAV or AIFF sound files.
audacity.sourceforge.net