FLAC is a Free Lossless Audio Codec. The FLAC format supports streaming, seeking, and archival, and gives 25-75% compression on typical CD audio. Input plugins for Winamp and XMMS are also provided.
FLAC for lossless compression.
The article doesn't delve into this much, but
FLAC is the lossless equivalent of Vorbis, is also patent free, and can even use Ogg as the stream transport.
A deduplicating backup program.
A graphical temperature monitor for Linux.