lossyWAV
lossyWAV offers almost lossless audio conversion and it reduces the size of the output file substantially, compared to the original lossless input file.
Spdifer
Spdifer is a DirectShow filter enabling media players to passthrough multi-channel sound to the digital output without any change.
OptimFROG
OptimFROG helps you reduce the memory space occupied by your music collection and also to restore the original files, using a method similar to ZIP compression.
FLAC
FLAC (stands for Free Lossless Audio Codec) is a compression tool which can handle FLAC, OGG and WAV formats.