TAK!

Ogg Vorbis is a fully open, general-purpose compressed audio format for mid to high quality (8kHz-48.0kHz, 16+ bit, polyphonic) audio and music at fixed and variable bitrates from 16 to 128 kbps/channel. This places Vorbis in the same competitive class as audio representations such as MPEG-4 (AAC), and similar to, but higher performance than MPEG-1/2 audio layer 3, MPEG-4 audio (TwinVQ), WMA and PAC.

The Matroska Multimedia Container is an open standard free container format, a file format that can hold an unlimited number of video, audio, picture, or subtitle tracks in one file. It is intended to serve as a universal format for storing common multimedia content, like movies or TV shows.

WavPack is a completely open audio compression format providing lossless, high-quality lossy, and a unique hybrid compression mode. Although the technology is loosely based on previous versions of WavPack, the new version 4 format has been designed from the ground up to offer unparalleled performance and functionality.

Speex is a patent-free audio compression format designed for speech and also a free software speech codec that may be used on VoIP applications and podcasts.

Apple Lossless (also known as ALAC) is an audio codec developed by Apple Inc. for lossless data compression of digital music.

Nero AAC reference quality MPEG-4 and 3GPP audio codec

[No longer maintained, but downloadable] FLAC Frontend is a Windows GUI (Graphical User Interface) for FLAC. Windows users are used to graphical programs (Rather than a command line). That's why Speek made FLAC frontend. The frontend only makes a batch file for flac.exe and executes it.

Shamrock Soft developed and published first free Windows Phone player which plays exclusively flac files.